To answer this question it is best to remember SOH CAH TOA.SOH: sin(angle)=opposite (length of side opposite the angle)/hypotenuse (length).CAH: cos(angle)=adjacent (length of side next to the angle)/hypotenuse.TOA: tan(angle)= opposite/adjacent.
In a question like this you will be given an angle within the triangle, for example 60 degrees, and the length of one side, for example the hypotenuse as 13cm. If the side labeled x is adjacent to the angle then we will use CAH: cos(angle)= adjacent side/hypotenuse
So, cos60= adjacent/13Rearrange the equation to get adjacent = cos60 x 13Answer= 6.5