Question

Write sin 64° in terms of cosine.

Answer 1

sin (90-x)=cos (x) ( Trigonometry Indentity)

So, sin (90-26)= cos (26) = sin (64)

Cosine and Sine values appear to be related complementary, as in the above answer. If you’ve seen the pattern such as

cos (0) = sin (90)

cos (30) = sin (60)

cos (45) = sin(45)

cos(60) = sin (30)

cos (90) = sin (0),

The sum of the angles equal 90 degrees.

Answer 2

Explanation:

Rule

The sin of any angle = cos(90 - the angle used for the sine)

Sin(64) = cos(90 - 64)

Sin(64) = cos(26)

Check

Sin(64) = 0.8988

Cos(26) = 0.8988