Question

if theta is equal to 30 show that cos 2 theta is equal to 2 cos squared theta minus one ​

Answer 1

Answer:

given:-

Ø = 30°

to prove that,

cos2Ø = 2cos²Ø-1

cos2×30 = 2cos²30-1

cos60 = 2×(√3/2)²-1

1/2 = 2×3/4-1

1/2 = 3/2-1

1/2 = 1/2

since LHS = RHS

Hence proved

Answer 2

Answer:

Ayush here..

Given:- Φ =30°.

A/Q,

Cos2Φ = 2Cos²Φ - 1

Cos2×30° = 2Cos²30 - 1

Cos60° = 2×(√3/2)² - 1

1/2 = 2 × 3/4 - 1

1/2 = 3/2 - 1

1/2 = 3 - 2/2

1/2 = 1/2..

Hence,proved..

HOPE IT HELPS..

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