smiles@Gmat wrote:What is the perimeter of a traingle ABC ,whose area is 24 units ?
1) Angle b = 120 degree
2) Traingle ABC is isosceles
Please explain the solution.
Area of triangle = 24 sq units
(1) Angle b = 120º does not give any further info on the length of the sides; NOT sufficient.
(2) Triangle ABC is isosceles implies 2 sides of the triangle are equal but we don't know which 2 sides are equal; NOT sufficient.
Combining (1) and (2), since angle b = 120º and ABC is an isosceles triangle, so it clearly implies that the angles a and c are equal = 30º each. This implies that we get two 30-60-90 triangles, as shown below:
In a 30°-60°-90° triangle the sides are in the ratio 1 : 2 : √3
We can hence find the perimeter of triangle ABC; SUFFICIENT.
The correct answer is
C.
