Taking A = 30°, verify that (i) cos 4 A - sin 4 A = cos 2A (ii) 4 cos A cos (60° - A) cos (60° + A) = cos 3A.

(i) To verify, cos 4 A - sin 4 A = cos 2A Substituting value of A in L.H.S. of the above equation, we get : Substituting value of A in R.H.S. of the above equation, we get : ⇒ cos 2A = cos 2(30°) = cos 60° = . Since, L.H.S. = R.H.S. Hence, proved that cos 4 A - sin 4 A = cos 2A. (ii) To verify, 4 cos A cos (60° - A) cos (60° + A) = cos 3A. Substituting value of A in L.H.S. of the above equation, we get : Substituting value of A in R.H.S. of the above equation, we get : Since, L.H.S. = R.H.S. Hence, proved that 4 cos A cos (60° - A) cos (60° + A) = cos 3A

Mathematics

Taking A = 30°, verify that
(i) cos⁴ A - sin⁴ A = cos 2A
(ii) 4 cos A cos (60° - A) cos (60° + A) = cos 3A.

Trigonometrical Ratios

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Mathematics

Taking A = 30°, verify that
(i) cos⁴ A - sin⁴ A = cos 2A
(ii) 4 cos A cos (60° - A) cos (60° + A) = cos 3A.

Trigonometrical Ratios

Related Questions

Find the values of :
sec 30° tan 60° + sin 45° cosec 45° + cos 30° cot 60°

Mathematics

Taking A = 30°, verify that(i) cos4 A - sin4 A = cos 2A(ii) 4 cos A cos (60° - A) cos (60° + A) = cos 3A.

Trigonometrical Ratios

Related Questions

Find the values of :sec 30° tan 60° + sin 45° cosec 45° + cos 30° cot 60°

Taking A = 30°, verify that
(i) cos⁴ A - sin⁴ A = cos 2A
(ii) 4 cos A cos (60° - A) cos (60° + A) = cos 3A.

Find the values of :
sec 30° tan 60° + sin 45° cosec 45° + cos 30° cot 60°