Class 11th Maths – RD Sharma Chapter 8 : Trigonometric Formulae – Very Short Answer Questions (VSAQs) Solutions (Step-by-Step Guide)

1. If (cos α + cos β)² + (sin α + sin β)² = λ cos²( (α – β) / 2 ), write the value of λ. Watch Solution
2. Write the value of sin π/12 sin 5π/12 Watch Solution
3. If sin A + sin B = α and cos A + cos B = β, then write the value of tan((A + B)/2) Watch Solution
4. If cos A = m cos B, then write the value of cot((A + B)/2) cot((A – B)/2) Watch Solution
5. Write the value of the expression (1 – 4 sin 10° sin 70°) / (2 sin 10°) Watch Solution
6. If A + B = π/3 and cos A + cos B = 1, then find the value of cos((A – B)/2) Watch Solution
7. Write the value of sin π/15 sin 4π/15 sin 3π/10 Watch Solution
8. If sin 2A = λ sin 2B, then write the value of (λ + 1)/(λ – 1)  Watch Solution
9. Write the value of (sin A + sin 3A)/(cos A + cos 3A) Watch Solution
10. If cos (A + B) sin (C – D) = cos (A – B) sin (C + D), then write the value tan A tan B tan C. Watch Solution