Using sine rule and cosine rule, the angles from smallest to largest is A,B,C.
Using the cosine rule;
a^2 = b^2 + c^2 - 2bc cos A
When;
a = 9 cm
b = 16 cm
c = 18 cm
9^2 = 16^2 + 18^2 - (2 × 16 × 18) cos A
81 = 256 + 324 - (576) cos A
81 = 580 - 576 cos A
81 - 580 = - 576 cos A
cos A = (81 - 580)/ - 576
A = cos-1[(81 - 580)/ - 576]
A = 30°
Using the sine rule;
a/sin A = b/sinB
asinB = bsinA
sinB = bsinA/a
B = sin-1(bsinA/a)
B = sin-1[(16 × sin30)/9]
B = 63°
Now;
A + B + C = 180(Sum of angles in a triangle)
C = 180 - ( A + B)
C = 180 - ( 30 + 63)
C = 87°
The angles are A, B, C.
Learn more about cosine rule: https://brainly.com/question/3240813
