What is a four-sided polygon with four congruent sides and acute angles?

Answer 1

A rhombus has 4 equal sides, 2 acute angles and 2 obtuse angles.

If you are looking for a polygon with 4 equal sides and ALL acute angles, that can't exist.

An acute angle is an angle of less than 90 degrees, so four of them add up to less than

360 degrees. But the four angles inside a four-sided polygon must add up to 360 degrees,

so they can't all be acute.