#### Answer

cos α = $\frac{b}{c}$
sin β = $\frac{b}{c}$
Thus cos α = sin β

#### Work Step by Step

Lets take question 1 diagram:
as we know cos α = $\frac{adjacent}{hypotenus}$
for question 1 , cos α = $\frac{12}{13}$
sin β = $\frac{opposite}{hypotenus}$
for question 1 , sin β = $\frac{12}{13}$
Therefore we can say that cos α = sin β = $\frac{12}{13}$