Question

find the area of triangle this side is 18 cm and 10cm and perimeter is 42cm​

Answer 1

Using the formulas

A=s(s﹣a)(s﹣b)(s﹣c)

P=a+b+c

s=a+b+c

2

Solving forA

A=1

4﹣P4+4P3a+4P3b﹣4(Pa)2﹣12P2ab﹣4(Pb)2+8Pa2b+8Pab2=1

4·﹣424+4·423·18+4·423·10﹣4·(42·18)2﹣12·422·18·10﹣4·(42·10)2+8·42·182·10+8·42·18·102≈69.64912cm²