Question

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

Answer 1

Answer:

Area of a triangle = 21√11 cm².

Step-by-step explanation:

Solution:

a=18

b=10

c=?

a + b + c = perimeter of triangle

18 + 10 + c = 42

28 + c = 42

c = 42-28

c = 14 cm

s = perimeter/2

s = 42/2

s = 21 cm

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

= √21 (21-18) (21-10) (21-14)

= √21 (3) (11) (7)

= √7×3×3×11×7

= 7×3√11

=21√11 cm²