Calculate the area of a triangle two sides of which
are 18 cm and 10 cm and the perimeter is 42 cm.
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Step-by-step explanation:
use Pythagoras theorem
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Step-by-step explanation:
perimeter of triangle = Sum of all sides
42 = 18 + 10 + Third side
Third side = 42 - 28 = 14 cm
S = (a + b + c)/2
S = 42/2 = 21 cm
Area of triangle from Heron's formula
= √S(S - a)(S - b)(S - c)
= √21(21 - 18)(21 - 10)(21 - 14)
= √21 × 3 × 11 × 7
= √21 × 21 × 11
= 21√11 cm²
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