cos 40° + cos 80° + cos 160° + cos 240°= (a) 0 (b) 1 (c) 1/2 (d) -1/2 Watch Solution
sin 163° cos 347° + sin 73° sin 167° = (a) 0 (b) 1/2 (c) 1 (d) none of these Watch Solution
If sin 2θ + sin 2ϕ = 1/2 and cos 2θ + cos 2ϕ = 3/2, then cos²(θ – ϕ) = (a) 3/8 (b) 5/8 (c) 3/4 (d) 5/4 Watch Solution
The value of cos 52° + cos 68° + cos 172° is (a) 0 (b) 1 (c) 2 (d) 3/2 Watch Solution
The value of sin 78° – sin 66° – sin 42° + sin 6° is (a) 1/2 (b) –1/2 (c) –1 (d) none of these Watch Solution
If sin α + sin β = a and cos α – cos β = b, then tan((α – β)/2) = (a) -a/b (b) -b/a (c) √(a² + b²) (d) none of these Watch Solution
cos 35° + cos 85° + cos 155° = (a) 0 (b) 1/√3 (c) 1/√2 (d) cos 275° Watch Solution
The value of sin 50° – sin 70° + sin 10° is equal to (a) 1 (b) 0 (c) 1/2 (d) 2 Watch Solution
sin 47° + sin 61° – sin 11° – sin 25° is equal to (a) sin 36° (b) cos 36° (c) sin 7° (d) cos 7° Watch Solution
If cos A = m cos B, then cot((A + B)/2) cot((B – A)/2) = (a) (m – 1)/(m + 1) (b) (m + 2)/(m – 2) (c) (m + 1)/(m – 1) (d) none of theseWatch Solution
If A, B, C are in A.P., then (sin A – sin C)/(cos C – cos A) = (a) tan B (b) cot B (c) tan 2B (d) none of these Watch Solution
If sin(B + C – A), sin(C + A – B), sin(A + B – C) are in A.P., then cot A, cot B, cot C are in (a) GP (b) HP (c) AP (d) none of these Watch Solution
If sin x + sin y = √3 (cos y – cos x), then sin 3x + sin 3y = (a) 2 sin 3x (b) 0 (c) 1 (d) none of these Watch Solution
The value of sin(π/18) + sin(π/9) + sin(2π/9) + sin(5π/18) is given by (a) sin(7π/18) + sin(4π/9) (b) 1 (c) cos(π/6) + cos(3π/7) (d) cos(π/9) + sin(π/9) Watch Solution
Chapter 8: Transformation Formulae– R. D. Sharma Class 11th Maths