triangle
A rhombus.
a rhombus
56678 Shape is called a rhombus
I only know it's not a polygon
A rhombus
An isosceles triangle fits the description given or an equilateral triangle which has 3 equal sides and 3 equal acute angles.
Any shape with 4 acute angles must have more than 4 sides. Any shape with more than 4 sides can have 4 acute angles (but doesn't have to).
A rhombus is a shape having two acute angles and four equal sides.
With no acute or obtuse angles, the shape must only have right angles. For a quadrilateral, that limits it to a square or rectangle. Because each side has a different length than the one next to it, it has to be a rectangle.(Or, it could be a shape with any amount of sides above 4, as long as the angles are all right angles)
Impossible.
An isosceles triangle is a shape that has at least 2 sides that are the same length. This forces the angles to be acute.