Question

find the area of triangle two sides of which are 18 cm and 10cm and semi perimeter is 21 cm

Answer 1

ANSWER:

21√11 cm

STEP BY STEP EXPLANATION :

AB = 18 CM

BC = 10 CM

AC = x cm

First finding side AC

HERE. semi perimeter is 21 cm

Now semi perimeter = PERIMETER/2

SO perimeter = semi perimeter × 2

= 21× 2

= 42 cm

now perimeter of triangle = sum of all side

AB + BC + AC = 42

18+ 10 + x = 42

28 + x = 42

x = 42 - 28

x = 14cm

SO , AC IS 14 cm

NOW AREA OF TRIANGLE IS √s (s - a)(s - a) (s - a)

so √21 (21 - 18)(21 - 10) ( 21 - 14)

√21 × 3 × 11 × 7

√7 × 3 × 3 × 11 × 7

7 × 3√11

21√11 cm

SO AREA OF TRIANGLE IS 21√11 cm