Multiple choice

If cot A + cosec A = 3 and A is in acute angle, then what is the value of cos A? यदि cot A + cosec A = 3 और A एक न्यूनकोण है, तो cos A का मान क्या है?

  1. 1

  2. 1/2

  3. 3/4

  4. 4/5

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Write cot A + cosec A = cos A/sin A + 1/sin A = (cos A + 1)/sin A = 3. Square: (1 + cos A)²/sin²A = 9. Using sin²A = 1 - cos²A = (1-cos A)(1+cos A), we get (1+cos A)/(1-cos A) = 9. Solving gives cos A = 4/5. Option A (1), B (1/2), C (3/4) don't satisfy the equation.