Question

Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm.

Answer 1

SOLUTION

Two sides of the triangle = 18cm and 10cm
Perimeter of the triangle = 42cm
Third side of triangle = 42 - (18+10) cm = 14cm
Semi perimeter of triangle = 42/2 = 21cm
Using heron's formula,
Area of the triangle = √s (s-a) (s-b) (s-c)
                                       = √21(21 - 18) (21 - 10) (21 - 14) cm2
                                       = √21 × 3 × 11 × 7 m2
                                       = 21√11 cm2

Answer 2

TREE ANS:

Two sides of the triangle = 18cm and 10cm

Perimeter of the triangle = 42cm

Third side of triangle = 42 - (18+10) cm = 14cm

Semi perimeter of triangle = 42/2 = 21cm

Using heron's formula,

Area of the triangle = √s (s-a) (s-b) (s-c)

                                      = √21(21 - 18) (21 - 10) (21 - 14) cm2

                                      = √21 × 3 × 11 × 7 m2

                                      = 21√11 cm2