Question
The ratio of the present ages of Ram and Ramesh is 3 :
5. After 7 years the ratio of their ages will be 4 : 5. Find the present age of Ramesh.Solution
Let the present age of Ram and Ramesh be 3x and 5x According to the question, (3x + 7)/(5x + 7) = (4/5) ⇒ 15x + 35 = 20x + 28 ⇒ 35 - 28 = 20x - 15x ⇒ 5x = 7 ⇒ x = 7/5 So, the present age of Ramesh = 5 × (7/5) ⇒ 7 years
- If cos θ = (4x² – 1)/(1 + 4x²) then find the value of sin q.

sin2 17˚ + sin2 19˚ + sin2 21˚ + sin2 23˚ + ……… + sin2 77˚ = ?
- If X = 15°, find the value of:
sin²(3X) + cos²(4X) - tan²(2X) If 7sin²θ + 3cos²θ = 4, then find the value of θ?
- In a triangle ABC, if 5∠A = 3∠B = 15∠C, then find the value of cosA + sin(C + 25 ° )
Find the exact value of cos120°
Find the value of the given trigonometric expression:
(sin 15°cos 75° + cos²15°) × sin 30° + (cos 60°tan 45°) × sec 60°
...[(sinx – 2sin 3 x)/(2cos 3 x – cosx)] 2  + 1, x ≠45 o , is equal to: