Question

The value of e for which cos (10° + 0) = sin 30°, is
(A) 50°
(B) 40°
(C) 80
20°

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Answer 1

Answer:

Cos (10°+ ∅ ) = sin30°

Cos (10°+∅) = sin (90°-60°)

Cos (10°+∅) = cos 60°

=> 10°+ ∅ = 60°

∅=50°

Answer 2

Answer:

The sum of the values for 9 = 0, 10°, 20°, 30°, &c. to 80°, is a sin B (1 + 2 cos 10° + 2 ... is c sin D x (2 cos 40°-H 2 cos 20° -- 1): and the sum of the values for 6 = 50°

option (A) is correct answer