To find the perimeter of a triangle, use the equation P=A+B+C, where P is the perimeter and A, B and C are the lengths of each of the three sides of a triangle. The perimeter of a triangle is the distance around all three sides.Continue Reading
Gather a ruler, a piece of paper and a writing utensil. A calculator may be useful to complete the equation.
Measure the sides of the triangle using the ruler. Write down the length of each of the sides of the triangle on a piece of paper. The first side of the triangle is considered the A side, the second side of the triangle is considered the B side and the third or longest side of the triangle is known as the C side of the triangle.
Write down the original equation of p=a+b+c on a piece of paper. Replace A with the measured length of the A side of the triangle. Replace B with the measured length of the B side of the triangle. Replace C with the value found in measuring the C side of the triangle. Add the three values together. This is the perimeter of the triangle.