Which quadrilaterals always have four right angles?

What is the solution set of the quadratic inequality x^2-5< or equal to 0

The median am of triangle ∆abc is half the length of the side towards which it is drawn, bc . prove that triangle ∆abc is a right triangle, and find angle mac and abm

Ron has 8 caps and 4 of his caps are blue. thes rest of his cap are red. how many of ron's caps are red