# Need help for geometry proof

• March 31st 2009, 10:23 AM
Calaghan
Need help for geometry proof
I need to write a proof and prove that: any triangle inscribed in a semicircle is a right triangle.

I realize that it is right, but I am unsure how to prove that it is true.

Can anyone help me with an idea of where to start?

Thanks.
• March 31st 2009, 11:19 AM
Plato
Realize that the diameter of the circle is the hypotenuse of the triangle.
Any inscribed angle in a circle measures one-half the intercepted arc.
But that is the “other” semicircle which measures $\pi$.
• April 1st 2009, 06:56 AM
Calaghan
I'm confused with what the intercepted arc is and therefore both the second and third lines confuse me.