Triangle 101: (tried to to 101 things about triangles, and copied from a website) The sum of all three interior angles of a triangle is always equal to 180⁰ A triangle has 3 sides. In triangle ABC, the sides are AB, BC, and CA. The angle formed by any two sides of a triangle is the angle of the triangle, denoted by the symbol ∠. A triangle has three angles. The three angles of the triangle ABC are ∠ABC, ∠BCA, and ∠CAB. These angles are also called ∠B, ∠C, and ∠A, respectively. The point of intersection of any two sides of a triangle is known as a vertex. A triangle has three vertices. In triangle ABC, the vertices are A, B, and C. \The sum of all three interior angles of a triangle is always equal to 180⁰. The sum of the length of any two sides of a triangle is always greater than the length of the third side. The area of a triangle is equal to half of the product of its base and height. The area of a triangle is the region that the triangle occupies in 2d space. The area of different triangles differs based on their size. If we know the base length and height of a triangle, we can determine its area. It is expressed in square units. So, the Area of a triangle = ½ (Product of base and height of a triangle) In the triangle PQR, PQ, QR, and RP are the sides. QR is the triangle’s base, and PS is the triangle’s height. PS is perpendicular from vertex P to the side QR. So, to find the area of △PQR, we use the following formula: Area △PQR = ½ (Product of base and height of a triangle) Or, Area △PQR = ½ (QR X PS) The perimeter of a triangle is the sum of the length of all sides of the triangle. So, the perimeter of the triangle = Sum of all three sides. In triangle PQR, the perimeter will be the sum of the three sides, i.e., PQ, QR, and RP. So, Perimeter of △PQR = PQ + QR + RP.
