### Home > GC > Chapter 12 > Lesson 12.1.4 > Problem12-38

12-38.

Examine the diagram at right.

1. Explain why $y=\sin\theta$ and$x=\cos\theta$.

Use the diagram to write $\sin\theta=$ ?

2. According to this diagram, what is $(\sin\theta)^2+(\cos\theta)^2$? Explain how you know.

3. Does this relationship appear true for all angles? Use your calculator to find $(\sin23^\circ)^2+(\cos23^\circ)^2$ and $(\sin81^\circ)^2+(\cos81^\circ)^2$. Write down your findings.