Question

if sinA+sin2A=1,then cosA+cos4A=?​

Answer 1

Answer:

$cos^{2} A$+$cos^{4} A$ = 1

Step-by-step explanation:

( I think your question is mistyped . It should be like

If sinA + $sin^{2} A$ = 1 , then find $cos^{2} A$+$cos^{4} A$ )

sin A + sin² A = 1  (given)

=> sin A = 1 - sin²A

=> sin A = cos²A ----------- (1)

on squaring both sides we get,

sin²A = cos⁴A ----------- (2)

∴ $cos^{2} A$+$cos^{4} A$

= cos²A + sin²A  from (2)

= 1