Question

Sin (3x+19)=Cos(5x-25)

What is the value of x?
A) 6
B) 12
C) 18
D) 24

Answer 1

12 B
Took the test before

Answer 2

B

Explanation:

Using the cofunction identity

sin x = cos(90 - x)

Given

sin(3x + 19) = cos(5x - 25), then

3x + 19 = 90 - (5x - 25)

3x + 19 = 90 - 5x + 25

3x + 19 = 115 - 5x ( add 5x to both sides )

8x + 19 = 115 ( subtract 19 from both sides )

8x = 96 ( divide both sides by 8 )

x = 12 → B