Question

Evaluate cos2 19 + cos2 71

Answer 1

Answer:

i love these questions thanks for that.

Answer 2

$\cos^2 19+\cos^2 71=1$

Step-by-step explanation:

We have,

$\cos^2 19+\cos^2 71$

To find, the value of $\cos^2 19+\cos^2 71=?$

∴ $\cos^2 19+\cos^2 71$

$=\cos^2 (90-71)+\cos^2 71$

$=\sin^2 71+\cos^2 71$

Using the trigonometric identity,

$\sin^2 71+\cos^2 71=1$

= 1

Using the trigonometric identity,

$\sin^2 A+\cos^2 A=1$

Hence, $\cos^2 19+\cos^2 71=1$