Geometry

no, a2= c2-b2

Guest:

no, a2= c2-b2

a ²=c ²-c ²
Hi Guest,
You are right,
This could easily have been Pythagoras Theorem
And often with Pythagoras the hypotenuse is called c
In which case your answer is completely correct.
BUT
The hypotenuse does not have to be called c.
It can be called anything.
This is important for you to understand and remember.

By the way, I used the 'sup' button above the smilies to get the indices where they belong. 'sup' stands for superscript.

Guest:

a2=b2+c2-2(bc)cosA

This is cosine rule. It is probably better written like

a ²=b ²+c ²- (2bcCosA)

That way you are less likely to make a mistake when you work out your answer.