The mnemonic SOH CAH TOA is intended to remind you of the relationship between trig functions and sides of a right triangle. Here, the hypotenuse of the triangle and the side adjacent to the given angle are marked, so the relationship of choice is ...
Cos = Adjacent/Hypotenuse
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Using the values shown, we have ...
cos(15°) = x/99
Solving for x gives ...
x = 99·cos(15°) ≈ 95.6
The length of the side marked x is about 95.6 units.
To get 4 or fewer correct, at least 2 answers have to be wrong. And the probability of that is: 3/4 x 3/4=9/16 1-9/16=probability that 4 or fewer are correct=7/16 ☺☺☺☺
