Question

Two adjacent sides of a parallelogram are 21 cm and 20cm. The diagonal joining the end points of those two side is 29cm. The area of parallelogram is

Answer 1

Hi mate ,

First we make diagram

Then we see there is two triangles

so by using heron's formula

so we calculate area

$s = \frac{21 + 20 + 29}{2}$

$s = 35$

so now put the value of s in heron's formula

$a = \sqrt{s(s - a)(s - b)(s - c)}$

$a = \sqrt{35(35 - 20)(35 - 21)(35 - 29}$

$a = \sqrt{35 \times 15 \times 14 \times 6}$

$a = \sqrt{44100}$
$a = 210$

So, here is two tringle so now we multiply value if a with 2

Total area= 210×2

=420

Hope this helps you

Be brainlist