One side of the triangle is 10, the second is 4 cm shorter, and the third is 5 cm longer than the first. What is the perimeter of the triangle?
1) Find the length of the second side of the triangle. If it is 4 cm shorter (i.e. less) than the first side of the triangle, then subtract 4 cm from the length of the first side.
10 – 4 = 6 (cm).
2) Find the length of the third side of the triangle. If the third side is 5 cm longer than the first side of the triangle, then add 5 cm to the length of the first side.
10 + 5 = 15 (cm).
3) Find the perimeter of the triangle. The perimeter of a triangle is equal to the sum of the lengths of its three sides. P = a + b + c.
P = 10 + 6 + 15 = 31 (cm).
Answer. 31 cm.
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