Answer:
109.5; B
Explanation:
From your identity,
CosA = adjacent/ hypothenus
A represent an arbitrary angle between the sides in question.
In the question above, A=64
Hypothenus is the longest side and adjacent is the side just below the angle .
In the above case,
Hypothenus= X
adjacent =48
This means;
Cos64 = 48 /X
X = 48 / cos64; [ from cross multiplication and diving through by cos64]
X = 48 /0.4383 [ cos64 in radian = 0.4383]
= 109.51
= 109.5 to the nearest tenth.
Note( do your calculation of angle in radian or else, you won't get the answer)