GMATprep - triangle inside circle

[jayhawk2001]

OA after a few reply. Please provide explanations.

What is the greatest possible area of a triangular region with one vertex
at the center of a circle of radius 1 and the other two vertices on the
circle ?

A. sqrt(3) / 4
B. 1/2
C. pi / 4
D. 1
E sqrt(2)

[AMalik]

Hi,
For greatest possible area, triangle should be an isosceles right angled triangle.
With one vertex at centre of the circle n other two on the circle.

Area will be=1/2*B*H

Base and Height are 1 (radius of the circle)

So, area should be 1/2*1*1 = 1/2

So, it should be B

Amit

[zozo123]

Hi,
For greatest possible area, triangle should be an equilateral triangle!!

its area is 1/2*B*H with B = 1 and H = sqrt(3)/2

The result is : A = sqrt(3)/4

[jayhawk2001]

Good call. OA is B.

An isosceles right angled triangle is the isosceles triangle with the
greatest area.

[simplythebest]

I would Still go with Option A.

An Equilateral triangle will have Maximum area.

Jay, I hope we can draw an Equi triangle with the above mentioned constraints in the Problem.

[f2001290]

I got a formula from Trigonometry to solve this:

Area of a Triangle = (1/2)ab sin(x)

where a,b are the sides of the triangle and x is the included angle between these two sides.

We have maximum area when x is 90, because sin(90) is 1.
whereas sin(60) is sqrt(3)/2

[wongee]

How can one assume that the angle formed at the center of the circle is 90 degrees?

Thanks!