Question

Two sides of a triangle are 18 cm and 10 cm and the perimeter is 42 cm. What will be the area of the triangle? (a) 14√11 cm² (b) 21√11 cm² (c) 35√11 cm² (d) 28√11 cm²​

Answer 1

Answer:

b) 21√11 cm²

Step-by-step explanation:

The sides of triangle given: a =18 cm, b = 10 cm

Perimeter of the triangle = (a + b + c)

42 = 18 + 10 + c

42 = 28 + c

c = 42 - 28

c = 14 cm

Semi Perimeter

s = (a + b + c) = 42/2 = 21 cm

By using Heron’s formula,

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

= √21(21 - 18)(21 - 10)(21 - 14)

= √21 × 3 × 11 × 7

= 21√11 cm2

Area of the triangle = 21√11 cm2.

Answer 2

Answer:

21√11cm²

Step-by-step explanation:

because area of a triangle is side × side × side.

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