If sides A and B of a triangle have lengths of 1 and 2 respectively, and the angle between them is (2pi)/3, then what is the area of the triangle?

1 Answer
Jan 16, 2018

The area is sqrt3/2; or, *0.866 *

Explanation:

You'll need the sine rule for area of the triangle.
The formula is:
Area of the triangleABC = 1/2*a*b*sin C
This drawing(sorry if it's clumsy) will show what I mean :
enter image source here
Here, angle C = (2pi)/3
sin C= sqrt 3/2
Plugging in the values;
a=1;
b=2;
sin {(2pi)/3} = sqrt3/2
Area of triangle ABC = 1/2*1*2*sqrt3/2 =sqrt3/2
*Do not forget to give the units...