Question

If 21 and -3k
are sides of a parallelogram find its area.
​

Answer 1

Step-by-step explanation:

Area of the parallelogram ABCD = Area of triangle ABD + Area of triangle BCD

Since both the triangles are same, Area of the parallelogram ABCD =2×( Area of triangle ABD)

Area of triangle with sides a, b, and c and s

=

2

a+b+c

is

s(s−a)(s−b)(s−c)

.

For triangle with sides 21 cm, 28 cm and 35 cm, s=

2

21+28+35

=42cm

Area of the triangle with sides 21 cm, 28 cm and 35 cm, =

42(42−21)(42−28)(42−35)

=

42×21×14×7

=

21×2×21×2×7×7

=21×2×7=294cm

2

Hence, Area of the parallelogram ABCD =2×( Area of triangle ABD) =2×294=588cm

2