An isosceles trapezoid has an acute angle of 60 degrees, the lateral side is 12 cm, the large base

An isosceles trapezoid has an acute angle of 60 degrees, the lateral side is 12 cm, the large base is 30 cm. Find the midline of the trapezoid.

Find the projection of the side to the base:

12 * cos (60) = 12 * 1/2 = 6 cm.

Since the trapezoid is rectangular, the smaller base will be equal to:

12 – 6 = 6 cm.

We calculate the length of the middle line by the formula: l = (a + b) / 2, where l is the length of the middle line, a and b are the base.

(12 + 6) / 2 = 9.