Trigonometry Examples

sin (105)

$\sin (105)$

Step 1

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

$\sin (75)$

Step 2

Split

$75$ into two angles where the values of the six trigonometric functions are known.

$\sin (30 + 45)$

Step 3

Apply the sum of angles identity.

$\sin (30) \cos (45) + \cos (30) \sin (45)$

Step 4

The exact value of

$\sin (30)$ is

$\frac{1}{2}$ .

$\frac{1}{2} \cos (45) + \cos (30) \sin (45)$

Step 5

The exact value of

$\cos (45)$ is

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

$\frac{1}{2} \cdot \frac{\sqrt{2}}{2} + \cos (30) \sin (45)$

Step 6

The exact value of

$\cos (30)$ is

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

$\frac{1}{2} \cdot \frac{\sqrt{2}}{2} + \frac{\sqrt{3}}{2} \sin (45)$

Step 7

The exact value of

$\sin (45)$ is

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

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

Step 8

Simplify

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

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Step 8.1

Simplify each term.

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Step 8.1.1

Multiply

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

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Step 8.1.1.1

Multiply

$\frac{1}{2}$ by

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

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

Step 8.1.1.2

Multiply

$2$ by

$2$ .

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

Step 8.1.2

Multiply

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

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Step 8.1.2.1

Multiply

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

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

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

Step 8.1.2.2

Combine using the product rule for radicals.

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

Step 8.1.2.3

Multiply

$3$ by

$2$ .

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

Step 8.1.2.4

Multiply

$2$ by

$2$ .

$\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}$

Step 8.2

Combine the numerators over the common denominator.

$\frac{\sqrt{2} + \sqrt{6}}{4}$

Step 9

The result can be shown in multiple forms.

Exact Form:

$\frac{\sqrt{2} + \sqrt{6}}{4}$

Decimal Form:

$0.96592582 \dots$