Question

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

Answer 1

$\huge\bold\red{Hey!}$

In ΔABC,

$a = 18 \: cm \\ b = 10 \: cm \\ perimeter = 42 \: cm$

Now,

$18 + 10 + c = 42 \\ 28 + c = 42 \\ c = 14 \: cm$

We have to find the Semi-perimeter-

$s = \frac{42}{2} \\ s = 21 \: cm$

Area of ΔABC,By Herons Formula-

$\sqrt{s(s - a)(s - b)(s - c)} \\ \sqrt{21(21 - 18)(21 - 10)(21 - 14} \\ \sqrt{21 \times 3 \times 11 \times 7} \\ \sqrt{4851} \\ {69.75 \: cm}^{2}$

Answer 2

Answer:

Answer in photo, hope it's helpful to you.