Isosceles triangle

• Feb 28th 2010, 04:59 AM
Stuck Man
Isosceles triangle
How do I find the are of an isosceles triangle with two sides length 4 and the inbetween angle is theta? I know the answer is 8 sin theta.
• Feb 28th 2010, 05:09 AM
e^(i*pi)
Quote:

Originally Posted by Stuck Man
How do I find the are of an isosceles triangle with two sides length 4 and the inbetween angle is theta? I know the answer is 8 sin theta.

Angle C = $\theta$

Since side c is opposite angle C it means that $A = B = 4$

The area of a circle is given by $\frac{1}{2}ab \sin \theta$
• Feb 28th 2010, 05:14 AM
Stuck Man
Yes I should have known that. Questions usually have different letters to the common rules. Do you recommend writing the rules with the usual letters a, b and c and then converting to the questions letters?
• Feb 28th 2010, 05:44 AM
e^(i*pi)
Quote:

Originally Posted by Stuck Man
Yes I should have known that. Questions usually have different letters to the common rules. Do you recommend writing the rules with the usual letters a, b and c and then converting to the questions letters?

Do what works best.

$\frac{1}{2}ab \sin (C) = \frac{1}{2}ac \sin(B) = \frac{1}{2}bc \sin(A)$

My favoured method is to change the symbols in the question to match the first expression