If sin²A − cos²A = 1/4, find the value of cos²A.
2025
If sin²A − cos²A = 1/4, find the value of cos²A.
- A.
5/8
- B.
3/8
- C.
1/2
- D.
1/4
Show answer & explanation
Correct answer: B
Let sin^2 A = x and cos^2 A = y. Then x + y = 1 and x - y = 1/4. Subtracting gives 2y = 3/4, so y = 3/8.