The cosine of a complementary angle is cos (90° - 59°) ≈ 0.857.
Solution:
Given that sin 59° ≈ 0.857.
To find the cosine of a complementary angle.
If two angles are complementary means, their sum is add up to 90°.
Complementary angle of 59° is (90° - 59° = 31°).
We know that,
The sine of any acute angle is equal to the cosine of the complementary angle.
That is sinθ = cos (90 - θ).
⇒ sin 59° = cos (90° - 59°)
≈ 0.857
Therefore the cosine of a complementary angle is cos (90° - 59°) ≈ 0.857.
