Perimeter of a triangle is found by using the formula P = a + b + c, where a, b and c are the sides of the triangle. Write the rule that is expressed by this formula in words.
The perimeter of a triangle is the sum of all its sides.
92. Perimeter of a triangle is found by using the formula (P = a + b + c), where a, b and c are the sides of the triangle. Write the rule that is expressed by this formula in words.
Rule in words: To find the perimeter of a triangle, add the lengths of all three sides.
Know the meaning: The perimeter is the total distance around the triangle.
Name the sides: Let the three sides be
(a)
(b)
(c)
Use the symbol for perimeter:
(P)
Add the first two sides:
(a + b)
Now add the third side:
((a + b) + c)
So, the formula becomes:
(P = a + b + c)
Units stay the same as the sides: If sides are in cm, perimeter is also in cm.
Quick example:
Sides are (a = 3 ext{cm}), (b = 4 ext{cm}), (c = 5 ext{cm}).
Add step by step:
(a + b = 3 + 4 = 7)
((a + b) + c = 7 + 5 = 12)
Perimeter: (P = 12 ext{cm})