Question

Find the value of cos 2 theta if 2 sin 2theta =root 3

Answer 1

2Sin 2A = root3 (I have taken A instead of theta)
Sin 2A = root3/2
we know that sin A = root3/2 when2A = 60
=> 2A=60
A=60/2 = 30
Cos 2 A= Cos 2 X 30 = Cos 60
we know cos 60 = 1/2
Hope It Helps :-)

Answer 2

2$sin^{2}$Ф=$\sqrt{3}$
$sin^{2}$Ф=$\sqrt{3}/2$

$cos^{2}$Ф=1-sin²Ф
⇒1-(√3/2)²
⇒1-$\frac{3}{4}$
⇒$\frac{1}{4}$

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