The perimeter of an isosceles triangle is 30cm. The length of each congruent side is 3cm more than the length of its base. Find the lengths of all the sides.
Let the congruent sides of an isosceles △ be x. Let the base of the isosceles △ be y According to the 1st condition, x+x+y=30 2x+y=30 According to the 2nd condition x=y+3 x−y=3 Solving equation (1) and (2) 2x+y=30 x−y=3 ------------------- 3x=33 x=333 x=11 By substituting x=11 in equation (1) 2x+y=30 2(11)+y=30 22+y=30 y=30−22 =8 ∴ The length of the sides of a △ are 11cm,11cm and 8cm.