Question

This is a class 10 maths trigonometry question

Answer 1

$\sec 2\theta = 2 cos 2\theta \\\\\implies \frac{1}{cos 2\theta} = 2 cos 2\theta\\\\\implies \frac {1}{2} = cos^2 \theta\\\\\implies \frac{1}{\sqrt2} = cos \theta\\\\\implies cos 45 = cos \theta\\\\\implies \theta = 45$

Mark brainliest if it helped ^^

Answer 2

Given,

sec2ϴ = 2cos2ϴ

→ 1/cos2ϴ = 2cosϴ

→ 1 = 2cosϴ×cosϴ

→ 1 = 2cos²ϴ

→ cos²ϴ = 1/2

→ cosϴ = 1/√2

→ cosϴ = cos45⁰

→ ϴ = 45⁰

Answer:- (3) 45⁰