Question

If 2Cos^2A+cosA-1=0 then A=?

Answer 1

Answer:

$A=0 \\A=90$

Step-by-step explanation:

As we have given in the question that

$2cos^{2}a+cosa-1=0$

$2cos^{2}2a+cosa=1$

$cosa[2cosa+1]=1$

From the above equation, we can see that

1.$cosa=1$

2.$2cosa +1=1$

$cosa=0$

Therefor values for A are, and the final answer would be

1. 0°

2.90°