Answer:
x=27
Step-by-step explanation:
cos and sin are complementary angles. There theta or x add up to 90 degree. Using the formula.
cos x=sin y where x+y=90 let set up the equation.
[tex] \cos(2x + 9) = \sin(x) [/tex]
[tex]2x + 9 + x = 90[/tex]
[tex]3x + 9 = 90[/tex]
[tex]3x = 81[/tex]
[tex]x = 27[/tex]
To check our identity plug x in the top equation
[tex] \cos(2 \times 27 + 9)) = \sin(27) [/tex]
[tex] \cos(63) = \sin(27) [/tex]
they both equal about 0.45 so it is true.
x=27