Trigonometry Examples

$2 \sin (135) \cos (135)$

Step 1

Apply the sine double-angle identity.

$\sin (2 \cdot 135)$

Step 2

Multiply $2$ by $135$ .

$\sin (270)$

Step 3

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

$- \sin (90)$

Step 4

The exact value of $\sin (90)$ is $1$ .

$- 1 \cdot 1$

Step 5

Multiply $- 1$ by $1$ .

$- 1$