Definition: The word 'acute-angled' refers to a geometric shape or polygon where all four sides have the same length but one side has a shorter length than the others. The term comes from the Greek words 'acute' which means straight, and 'angled', which means curved.
An acute-angled triangle has three angles that are equal to each other (both are 60 degrees). All of its interior angles measure less than 180 degrees and greater than 90 degrees. If one side is shorter than the others, the triangle will be obtuse and not have any angles with a straight line.
An acute-angled polygon can have more than three sides, but it's easier to describe when just two or three sides are given. An example of an acute-angled polygon with three sides would be a square (4 sides), pentagon (5 sides), or hexagon (6 sides).
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