# Thread: From Altitudes to Angle to Sides

1. ## From Altitudes to Angle to Sides

I dont know where to start

3. ## Re: From Altitudes to Angle to Sides

In most cases the altitude of the triangle is inside the triangle, like that image example

4. ## Re: From Altitudes to Angle to Sides

AB = c, BC = a, AC = b

24 b = 56 c = 21 a = twice area ABC

solve for b, c in terms of a and replace in

$a^2+c^2-2 a c \cos B=b^2$

we get

$\cos B=1/2$