Question

Given: △ABC,
m∠B=120°
AB=6, BC=10
Find: Area of △ABC

Answer 1

15 root 3

Explanation:

f interior angle is ∡B=120° - obtuse angle then exterior angle ∡B1=60°

In the obtuse triangle height hB is out of the triangle.

We can calculate height hB in this way sin °60= hB/BC => hB= BC * sin 60°

hB= 10 * √3/2= 5√3

Formula for the area of the triangle is A= AB*hB/2= 6*5√3/2=15√3

A=15√3

Good luck!!!

Answer 2

If interior angle is ∡B=120° - obtuse angle then exterior angle ∡B1=60°

In the obtuse triangle height hB is out of the triangle.

We can calculate height hB in this way sin °60= hB/BC => hB= BC * sin 60°

hB= 10 * √3/2= 5√3

Formula for the area of the triangle is A= AB*hB/2= 6*5√3/2=15√3

A=15√3

Good luck!!!