Question

Given the following triangle, what is the measure of the missing side?

Answer 1

Angle sum property:
55+angle+90= 180
angle=180-145
=35
If the use of calculator is permitted then calculate 1/cos 35 (or sec 35) and you will get 1.22 approximately.
Reason for doing this was that x(hypotenuse)/10(perpendicular) = sec theta .
therefore now you get:-
x/10=1.22
multiply both sides by 10 and get
x= 12.2
Answer is Option A.