simplifying trig equations

[tawdry matrix]

would someone be able to show me how to simplify this, the answer should be 2 but I don’t know how to get there

[sonic night]

Can you not just expand them out
You’d end up with
2cos^2(theata) + 2sin^2(theata)
2(cos^2 + sin^2)
cos^2 + sin^2 = 1
2x1 = 2