If sinA = 3/5 and cosB = 4/5, and both A, B in first quadrant, then sin(A + B) = ?
Show answer & explanation
Correct answer: C
Explanation
sinA = 3/5, cosB = 4/5
According to the formula:
sin(A + B) = sinA cosB + cosA sinB
cosA = 4/5, sinB = 3/5
sin(A + B) = (3/5)(4/5) + (4/5)(3/5)
= 12/25 + 12/25
= 24/25