Question

A lawn is in the form of an isosceles triangle. The cost of turfing it came to Rs. 1200 at Rs.4
per m2 . If the base be 40m long, find the length of each equal side.​

Answer 1

Answer:

Step-by-step explanation:

the area of isosceles triangle= 1200/4

                                               = 300m²

now area of the triangle = 1/2 x base x height

                                  300 = 1/2 x 40 x height

                                  300 x 2 = 40 x height

                                    600 = 40 x height

                                     15 = height

now in triangle ABC AND THE HEIGHT IS AD

Therefore AD is perpindcular bisector of the base

therefore BD = 1/2 x 40

                       = 20

now in triangle ABD

by phythagoras theorem

AB² = BD² + AD²

AB = √20² + 15²

AB = √ 400 + 225

AB = √625

AB = 25

The lenght of equal side of the isosceles triangle is 25 cm