How many acute angles can a quadrilateral have?

##0## ##1## ##2## or ##3##
The sum of the internal angles of a quadrilateral is ##360^@##.
Hence the maximum number of acute angles a quadrilateral can have is ##3## since the ##4##th angle will be forced to be greater than ##90^@##.
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.