Question Detail

MTH 101 MTH 101 Past Questions Objective Question

Question

Value of (cos15°/sin15°) - (sin15°/cos15°) is:

Options
A 1
B 1/√3
C √3
D none of these
Correct Answer
Correct Answer

Option D is the correct answer.

Detailed Explanation

cos15°/sin15° = cot15°, sin15°/cos15° = tan15°. So expression = cot15° - tan15° = (cos²15° - sin²15°)/(sin15°cos15°) = cos30°/((1/2)sin30°) = (√3/2)/((1/2)(1/2))? Let's compute properly: cot15° - tan15° = (cos15°/sin15°) - (sin15°/cos15°) = (cos²15° - sin²15°)/(sin15°cos15°) = cos30°/((1/2)sin30°) = (√3/2)/((1/2)(1/2)) = (√3/2)/(1/4) = (√3/2) × 4 = 2√3. 

Hint

Use trigonometric identities or exact values.

Question Info