Answer:
find b: since the triangle is right angle triangle apply the Pythagorean theorem
c²+b²=d²
b²=d²-c²
b²=16²-12²
b²=256-144
b²=112
b=√112 = 4√7
the sum of the angle of the triangle=180
( in top Δ abd ) sin Ф=opp/hyp
sinФ=b/d=4√7/16= √7/4 radian
convert to degrees : √7/4 *180/π= 37.91 almost 38 degrees
which makes A= 38 degrees ( adjacent angles are equal when they have common side and do not overlap)
find a=?? apply law of cosine
a²= d^2 + c^2 − 2dc cosA
a²=16² + 12²-2(16)(12)cos38
a =√(16² + 12²-2(16)(12)cos38)
a=9.87 rounded to the nearest hundredth
(i hope it is right )