Question

If sinA+sin2A=1 than find cos2A+cos4A

Answer 1

Answer:

The value you need to know here is 1.

Step-by-step explanation:

Before I solve this,

I need you to know this identity,

${ \sin }^{2} \gamma + { \cos }^{2} \gamma = 1$

From LHS,

$\sin( \alpha ) + { \sin }^{2} \alpha = 1 \\ \\ \sin( \alpha ) + { \sin }^{2} \alpha = { \sin }^{2} \alpha + { \cos }^{2} \alpha \\ \\ \sin( \alpha ) = { \cos }^{2} \alpha$

Using this value in RHS,

${ \cos }^{2} \alpha + { \cos }^{4} \alpha \\ \\ = { \cos }^{2} \alpha + { \sin}^{2} \alpha \\ \\ = 1$