Find the Exact Value sin((3pi)/4)cos(pi/12)-cos((3pi)/4)sin(pi/12)

$\sin (\frac{3 π}{4}) \cos (\frac{π}{12}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Simplify each term.

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.

$\sin (\frac{π}{4}) \cos (\frac{π}{12}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

The exact value of $\sin (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{2}}{2} \cos (\frac{π}{12}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

The exact value of $\cos (\frac{π}{12})$ is $\frac{\sqrt{6} + \sqrt{2}}{4}$ .

Split $\frac{π}{12}$ into two angles where the values of the six trigonometric functions are known.

$\frac{\sqrt{2}}{2} \cos (\frac{π}{4} - \frac{π}{6}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Apply the difference of angles identity $\cos (x - y) = \cos (x) \cos (y) + \sin (x) \sin (y)$ .

$\frac{\sqrt{2}}{2} (\cos (\frac{π}{4}) \cos (\frac{π}{6}) + \sin (\frac{π}{4}) \sin (\frac{π}{6})) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

The exact value of $\cos (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cos (\frac{π}{6}) + \sin (\frac{π}{4}) \sin (\frac{π}{6})) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

The exact value of $\cos (\frac{π}{6})$ is $\frac{\sqrt{3}}{2}$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} + \sin (\frac{π}{4}) \sin (\frac{π}{6})) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

The exact value of $\sin (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} + \frac{\sqrt{2}}{2} \sin (\frac{π}{6})) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

The exact value of $\sin (\frac{π}{6})$ is $\frac{1}{2}$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} + \frac{\sqrt{2}}{2} \cdot \frac{1}{2}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Simplify $\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} + \frac{\sqrt{2}}{2} \cdot \frac{1}{2}$ .

Simplify each term.

Multiply $\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2}$ .

Multiply $\frac{\sqrt{2}}{2}$ by $\frac{\sqrt{3}}{2}$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{2} \sqrt{3}}{2 \cdot 2} + \frac{\sqrt{2}}{2} \cdot \frac{1}{2}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Combine using the product rule for radicals.

$\frac{\sqrt{2}}{2} (\frac{\sqrt{2 \cdot 3}}{2 \cdot 2} + \frac{\sqrt{2}}{2} \cdot \frac{1}{2}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Multiply $2$ by $3$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{2 \cdot 2} + \frac{\sqrt{2}}{2} \cdot \frac{1}{2}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Multiply $2$ by $2$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{2} \cdot \frac{1}{2}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Multiply $\frac{\sqrt{2}}{2} \cdot \frac{1}{2}$ .

Multiply $\frac{\sqrt{2}}{2}$ by $\frac{1}{2}$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{2 \cdot 2}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Multiply $2$ by $2$ .

$\frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}) - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Combine the numerators over the common denominator.

$\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{6} + \sqrt{2}}{4} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Multiply $\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{6} + \sqrt{2}}{4}$ .

Multiply $\frac{\sqrt{2}}{2}$ by $\frac{\sqrt{6} + \sqrt{2}}{4}$ .

$\frac{\sqrt{2} (\sqrt{6} + \sqrt{2})}{2 \cdot 4} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Multiply $2$ by $4$ .

$\frac{\sqrt{2} (\sqrt{6} + \sqrt{2})}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Apply the distributive property.

$\frac{\sqrt{2} \sqrt{6} + \sqrt{2} \sqrt{2}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Combine using the product rule for radicals.

$\frac{\sqrt{2 \cdot 6} + \sqrt{2} \sqrt{2}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Combine using the product rule for radicals.

$\frac{\sqrt{2 \cdot 6} + \sqrt{2 \cdot 2}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Simplify each term.

Multiply $2$ by $6$ .

$\frac{\sqrt{12} + \sqrt{2 \cdot 2}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Rewrite $12$ as $2^{2} \cdot 3$ .

Factor $4$ out of $12$ .

$\frac{\sqrt{4 (3)} + \sqrt{2 \cdot 2}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Rewrite $4$ as $2^{2}$ .

$\frac{\sqrt{2^{2} \cdot 3} + \sqrt{2 \cdot 2}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Pull terms out from under the radical.

$\frac{2 \sqrt{3} + \sqrt{2 \cdot 2}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Multiply $2$ by $2$ .

$\frac{2 \sqrt{3} + \sqrt{4}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Rewrite $4$ as $2^{2}$ .

$\frac{2 \sqrt{3} + \sqrt{2^{2}}}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Pull terms out from under the radical, assuming positive real numbers.

$\frac{2 \sqrt{3} + 2}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Cancel the common factor of $2 \sqrt{3} + 2$ and $8$ .

Factor $2$ out of $2 \sqrt{3}$ .

$\frac{2 (\sqrt{3}) + 2}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Factor $2$ out of $2$ .

$\frac{2 (\sqrt{3}) + 2 (1)}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Factor $2$ out of $2 (\sqrt{3}) + 2 (1)$ .

$\frac{2 (\sqrt{3} + 1)}{8} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Cancel the common factors.

Factor $2$ out of $8$ .

$\frac{2 (\sqrt{3} + 1)}{2 (4)} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Cancel the common factor.

$\frac{2 (\sqrt{3} + 1)}{2 \cdot 4} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Rewrite the expression.

$\frac{\sqrt{3} + 1}{4} - \cos (\frac{3 π}{4}) \sin (\frac{π}{12})$

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the second quadrant.

$\frac{\sqrt{3} + 1}{4} - - \cos (\frac{π}{4}) \sin (\frac{π}{12})$

The exact value of $\cos (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{3} + 1}{4} - - \frac{\sqrt{2}}{2} \sin (\frac{π}{12})$

Multiply $- - \frac{\sqrt{2}}{2}$ .

Multiply $- 1$ by $- 1$ .

$\frac{\sqrt{3} + 1}{4} + 1 \frac{\sqrt{2}}{2} \sin (\frac{π}{12})$

Multiply $\frac{\sqrt{2}}{2}$ by $1$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} \sin (\frac{π}{12})$

The exact value of $\sin (\frac{π}{12})$ is $\frac{\sqrt{6} - \sqrt{2}}{4}$ .

Split $\frac{π}{12}$ into two angles where the values of the six trigonometric functions are known.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} \sin (\frac{π}{4} - \frac{π}{6})$

Apply the difference of angles identity.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\sin (\frac{π}{4}) \cos (\frac{π}{6}) - \cos (\frac{π}{4}) \sin (\frac{π}{6}))$

The exact value of $\sin (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cos (\frac{π}{6}) - \cos (\frac{π}{4}) \sin (\frac{π}{6}))$

The exact value of $\cos (\frac{π}{6})$ is $\frac{\sqrt{3}}{2}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} - \cos (\frac{π}{4}) \sin (\frac{π}{6}))$

The exact value of $\cos (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} - \frac{\sqrt{2}}{2} \sin (\frac{π}{6}))$

The exact value of $\sin (\frac{π}{6})$ is $\frac{1}{2}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} - \frac{\sqrt{2}}{2} \cdot \frac{1}{2})$

Simplify $\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} - \frac{\sqrt{2}}{2} \cdot \frac{1}{2}$ .

Simplify each term.

Multiply $\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2}$ .

Multiply $\frac{\sqrt{2}}{2}$ by $\frac{\sqrt{3}}{2}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{2} \sqrt{3}}{2 \cdot 2} - \frac{\sqrt{2}}{2} \cdot \frac{1}{2})$

Combine using the product rule for radicals.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{2 \cdot 3}}{2 \cdot 2} - \frac{\sqrt{2}}{2} \cdot \frac{1}{2})$

Multiply $2$ by $3$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{2 \cdot 2} - \frac{\sqrt{2}}{2} \cdot \frac{1}{2})$

Multiply $2$ by $2$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{4} - \frac{\sqrt{2}}{2} \cdot \frac{1}{2})$

Multiply $- \frac{\sqrt{2}}{2} \cdot \frac{1}{2}$ .

Multiply $\frac{1}{2}$ by $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{4} - \frac{\sqrt{2}}{2 \cdot 2})$

Multiply $2$ by $2$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} (\frac{\sqrt{6}}{4} - \frac{\sqrt{2}}{4})$

Combine the numerators over the common denominator.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2}}{2} \cdot \frac{\sqrt{6} - \sqrt{2}}{4}$

Multiply $\frac{\sqrt{2}}{2} \cdot \frac{\sqrt{6} - \sqrt{2}}{4}$ .

Multiply $\frac{\sqrt{2}}{2}$ by $\frac{\sqrt{6} - \sqrt{2}}{4}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2} (\sqrt{6} - \sqrt{2})}{2 \cdot 4}$

Multiply $2$ by $4$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2} (\sqrt{6} - \sqrt{2})}{8}$

Apply the distributive property.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2} \sqrt{6} + \sqrt{2} (- \sqrt{2})}{8}$

Combine using the product rule for radicals.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2 \cdot 6} + \sqrt{2} (- \sqrt{2})}{8}$

Multiply $\sqrt{2} (- \sqrt{2})$ .

Raise $\sqrt{2}$ to the power of $1$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2 \cdot 6} - ({\sqrt{2}}^{1} \sqrt{2})}{8}$

Raise $\sqrt{2}$ to the power of $1$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2 \cdot 6} - ({\sqrt{2}}^{1} {\sqrt{2}}^{1})}{8}$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2 \cdot 6} - {\sqrt{2}}^{1 + 1}}{8}$

Add $1$ and $1$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2 \cdot 6} - {\sqrt{2}}^{2}}{8}$

Simplify each term.

Multiply $2$ by $6$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{12} - {\sqrt{2}}^{2}}{8}$

Rewrite $12$ as $2^{2} \cdot 3$ .

Factor $4$ out of $12$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{4 (3)} - {\sqrt{2}}^{2}}{8}$

Rewrite $4$ as $2^{2}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{2^{2} \cdot 3} - {\sqrt{2}}^{2}}{8}$

Pull terms out from under the radical.

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - {\sqrt{2}}^{2}}{8}$

Rewrite ${\sqrt{2}}^{2}$ as $2$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{2}$ as $2^{\frac{1}{2}}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - {(2^{\frac{1}{2}})}^{2}}{8}$

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - 2^{\frac{1}{2} \cdot 2}}{8}$

Combine $\frac{1}{2}$ and $2$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - 2^{\frac{2}{2}}}{8}$

Cancel the common factor of $2$ .

Cancel the common factor.

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - 2^{\frac{2}{2}}}{8}$

Rewrite the expression.

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - 2^{1}}{8}$

Evaluate the exponent.

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - 1 \cdot 2}{8}$

Multiply $- 1$ by $2$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 \sqrt{3} - 2}{8}$

Cancel the common factor of $2 \sqrt{3} - 2$ and $8$ .

Factor $2$ out of $2 \sqrt{3}$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 (\sqrt{3}) - 2}{8}$

Factor $2$ out of $- 2$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 (\sqrt{3}) + 2 (- 1)}{8}$

Factor $2$ out of $2 (\sqrt{3}) + 2 (- 1)$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 (\sqrt{3} - 1)}{8}$

Cancel the common factors.

Factor $2$ out of $8$ .

$\frac{\sqrt{3} + 1}{4} + \frac{2 (\sqrt{3} - 1)}{2 (4)}$

Cancel the common factor.

$\frac{\sqrt{3} + 1}{4} + \frac{2 (\sqrt{3} - 1)}{2 \cdot 4}$

Rewrite the expression.

$\frac{\sqrt{3} + 1}{4} + \frac{\sqrt{3} - 1}{4}$

Simplify terms.

Combine the numerators over the common denominator.

$\frac{\sqrt{3} + 1 + \sqrt{3} - 1}{4}$

Add $\sqrt{3}$ and $\sqrt{3}$ .

$\frac{1 + 2 \sqrt{3} - 1}{4}$

Simplify by subtracting numbers.

Subtract $1$ from $1$ .

$\frac{0 + 2 \sqrt{3}}{4}$

Add $0$ and $2 \sqrt{3}$ .

$\frac{2 \sqrt{3}}{4}$

Cancel the common factor of $2$ and $4$ .

Factor $2$ out of $2 \sqrt{3}$ .

$\frac{2 (\sqrt{3})}{4}$

Cancel the common factors.

Factor $2$ out of $4$ .

$\frac{2 \sqrt{3}}{2 \cdot 2}$

Cancel the common factor.

$\frac{2 \sqrt{3}}{2 \cdot 2}$

Rewrite the expression.

$\frac{\sqrt{3}}{2}$

The result can be shown in multiple forms.

Exact Form:

$\frac{\sqrt{3}}{2}$

Decimal Form:

$0.86602540 \dots$

Find the Exact Value sin((3pi)/4)cos(pi/12)-cos((3pi)/4)sin(pi/12)

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