Angles in the right triangle

[ABC] is a triangle rectangle in B. D is the midpoint of [BC] and E belongs to [AC] in order to verify the relationship between the angles shown in the figure. Prove that [BE] is p...

Hidden Pythagorean

In the figure we have 4 squares, E and F belong to the diagonal of the square ABCD and the measure of the angle EAF is 45º. If S, S1 and S2 are the areas of the squares with diago...

Three squares

Prove that D, J and F are collinear and that J is the midpoint of [DF].

Volume of the frustum

What is the volume of a frustum?

Volume of a cylinder inscribed in a cone

What is the volume of a cylinder inscribed in a cone?