## Elementary Geometry for College Students (6th Edition)

sin α = $\frac{a}{c}$ cos β = $\frac{a}{c}$ thus sin α = cos β
Lets take question 1 diagram: as we know sin α = $\frac{opposite}{hypotenus}$ for question 1 , sin α = $\frac{5}{13}$ cos β = $\frac{adjacent}{hypotenus}$ for question 1 , cos β = $\frac{5}{13}$ Therefore we can say that sin α = cos β = $\frac{5}{13}$