The perimeter of an isosceles triangle is 80 cm. If the side that is not equal in length to any of the other two sides is 20 cm, find the length of each of the equal sides.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 1 i.e. 30 cm
Perimeter = 80 cm
length of an unequal side = 20 cm
P = 2a + b units [Where, P = Perimeter, a = length of two equal sides and b = length of base or unequal side]
P = 80 cm , b = 20 cm
P = 2a + b
80 = 2a + 20
2a = 60
a = 30 cm