Question

(i) cos 60° = (cos2 30° - sin2 30°).

✌️❤️ please give write ans​

Answer 1

Answer:

cos 60° = cos²30° - sin²30°

Step-by-step explanation:

To prove cos 60° = cos²30° - sin²30°

take the LHS

= cos 60°

= cos 2(30°)

= cos²30° - sin²30°

= RHS

LHS = RHS

hence proved

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Verification:

cos 60° = 1/2

cos²30° - sin²30° = $(\frac{\sqrt{3} }{2}) ^{2}$ - $(\frac{1}{2} )^{2}$  = 3/4 - 1/4

                            = (3-1)/4

                            = 2/4

                            = 1/2

hence cos 60° = cos²30° - sin²30°

verified

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Answer 2

Solution:

cos 60° = cos^2 30° - sin^2 30°

➪ LHS = cos 60°= 1/2

➪ RHS = cos^2 30° - sin^2 30°

➪ (√3/2)^2+(1/2)^2 = 3/4 - 1/4

➪ 3-1/4=2/4=> 1/2

꧁LHS= RHS꧂ . Hence, the result ✔︎✔︎✔︎