A) 20°
Step-by-step explanation:
Sine and cosine are co-function complements which means that value of sine of an angle is equal to the value of cosine of the complementary angles.
This can be represented by:
![\sin\theta=\cos(90\°-\theta)](/tpl/images/0423/6430/f309e.png)
![\cos\theta=\sin(90\°-\theta)](/tpl/images/0423/6430/e0eaa.png)
Given statement:
![cos\theta=\sin70\°](/tpl/images/0423/6430/13d37.png)
Applying co-function complements
![\cos\theta=\sin(90\°-\theta)](/tpl/images/0423/6430/e0eaa.png)
Since, we can represent 70° = 90°-20°
So
Thus,
makes the statement true.