Question

Write as a single term: sin(25°) cos(10°) − cos(25°) sin(10°).

Answer 1

Answer: cos (25° + 10°)

Step-by-step explanation: The expression:

sin(25°) cos(10°) − cos(25°) sin(10°)

is associated to the expression for the cosine of the sum of two angles that is:

cos (α+β) = sinα *cosβ -cosα*sinβ

Hence if we do α = 25° and β = 10°

by subtitution we get:

cos (25° + 10°) = sin(25°) cos(10°) − cos(25°) sin(10°)