Question

If the sides of a triangle are 6cm, 12cm and angle between them is 120º, then find it's area ?

Answer 1

Answer:

Consider the figure

Extend the side BC and draw perpendicular through A on it

AD is height and BC is base of triangle

1. ∠ABD=180-∠ABC=60°

Step-by-step explanation:

in 30-60-90 triangle side opp. to 60° is $\sqrt{3} /2$ of hypo.

hence AD =$\sqrt{3} /2$*6=3$\sqrt{3}$

Now area of triangle =$\frac{1}{2}$*Height*Base

=$\frac{1}{2}$*AD*BC=$\frac{1}{2}$*3$\sqrt{3}$*12=18$\sqrt{3}$

Area is 18$\sqrt{3}$ sq.cm  or 31.18 sq.cm