Learn about triangles, a type of polygon with three sides and three angles, in geometry. Find out the properties, types, perimeter and area formulas, and solved examples of triangles. This complete guide to geometric shapes includes every 2D geometric shape and all 3D geometrical shapes . Each geometric shape includes an image and a description. This guide also includes examples of geometric shapes art and a free printable geometric shapes chart pdf for students. This lesson explains the concept of a triangle and its properties. We will touch upon the basics of different types of triangles and also the famous Pythagorean Theorem. Triangles are classified into different types based on their angles and the lengths of their sides. Relations between angles and side lengths are a major focus of trigonometry. In particular, the sine, cosine, and tangent functions relate side lengths and angles in right triangles .
