# Math Help - Isosceles triangle

1. ## 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.

2. 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 $\frac{1}{2}ab \sin \theta$

3. 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?

4. 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