Question

How many acute angles can a quadrilateral have?

Answer 1

$0,1,2$ and $3$
Explanation :
The sum of the internal angles of a quadrilateral is ${360}^{\circ }$.

Hence the maximum number of acute angles a quadrilateral can have is $3$, since the $4th$ angle will be forced to be greater than ${90}^{\circ }$ .

In the following picture, the red square has no acute angles, the green kite has one acute angle, the blue rhombus has two and the gold kite has three.