The sides of a triangle r 6 7 and 8 cm. Find the size of the smallest angle?

Let the angle opposite to the side of 6 be C, then

cos C = (7^2 + 8^2 - 6^2)/(2 x 7 x 8)

cos C = 77/112

cos C = 0.6875

m of C = arc cosine(0.6875) = 46.57 degrees