geometry terms

an acut angle is less than 90 degrees but more than 0 degrees

acute triangle is a triangle whose sides angles are all acute.

an arc is a part of a circle.

a central angle is an  angle whose vertex is the center of a circle, and whose sides pass through a pair of points on the circle

A circle is a closed plane curve every point of which is equidistant from a fixed point within the curve

a chord is a  line segment on the interior of a circle with both its endpoints lying on the circle.

complementary angles is a pair of angles whose sum= 90