If $(2 \cos A+1)(2 \cos A-1)=0,0^{\circ}<A \leq 90^{\circ}$, then find the value of A.
Answer & explanation
Correct answer: option 4
( 2cosA - 1 ) ( 2cosA + 1 ) = 0
4cos2A - 1 = 0
cos2A = \(\frac{1}{4}\)
cosA = \(\frac{1}{2}\)
& we know , cos60º = \(\frac{1}{2}\)
So , A = 60º