Find the perimeter of the triangle if its mid-line is 6.9 and 10 cm.

Given:
triangle ABC,
OH – the middle line is parallel to the BC side,
КН – the middle line is parallel to the AB side,
OK – the middle line is parallel to the side of the speaker,
OH = 6 centimeters,
KН = 9 centimeters,
OK = 10 centimeters.
Find the lengths of the sides of the triangle P ABC -?
Decision:
Consider a triangle ABC. The middle line is half the length of the parallel side.
Then AC = 2 * OK;
AC = 2 * 10 = 20 (centimeters).
BC = 2 * OH;
BC = 2 * 6 = 12 (centimeters).
AB = 2 * KН;
AB = 2 * 9 = 18 (centimeters).
R ABC = 20 + 12 + 18 = 60 (centimeters)
Answer: 60 centimeters.