Question

Which value is equivalent to sin20°?

Answer 1

Answer:

Option C. cos70°

Step-by-step explanation:

we know that

If two angles are complementary, then the sine of one angle is equal to the cosine of the other angle and the cosine of one angle is equal to the sine of the other angle

Remember that

Tow angles are complementary , if the sum of their angles is equal to 90 degrees

so

If A+B=90°

then

sin(A)=cos(B)

cos(A)=sin(B)

In this problem we have

A=20°

B=90°-20°=70°

therefore

sin(20°)=cos(70°)

cos(20°)=sin(70°)