### Home > A2C > Chapter 8 > Lesson 8.1.7 > Problem 8-105

8-105.

Evaluate each of the following trig expressions without using a calculator. Homework Help ✎

sin(180°)

sin(360°)

sin(−90°)

sin(510°)

cos(90°)

tan(−90°)

Every point on the unit circle is defined as (cos θ, sin θ).

Where is 180° on the unit circle?

Where is the *y*-value at that point?

0

See part (a).

When an angle is negative, it opens clockwise from 0° on the unit circle.

Find an equivalent angle between 0° and 360° by subtracting 510 − 360. Notice that the reference

triangle is a 30°-60°-90° triangle. Find the sin 30°.

0.5

What is the *x*-value in this location?

0

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