The sum of angles of a triangle is 180 degrees.
In triangle PQR above a + b + c = 180 degrees
A right-angled triangle has one of its angles measuring 90 degrees. Triangle XYZ is a rightangled triangle since ∠XYZ= 90 degrees as shown
in the figure below.
An equilateral triangle has all sides equal and all angles equal to 60 degrees as shown below.
Triangle TRS is an Isosceles triangle because it has two sides equal (side TR & TS are equal) and two angles are equal (AngleTRS and angle TSR are eqaul).
(i) Draw a line AB.
(ii) With centres A and B and the same radius draw arcs to intersect at C.
(iii) Draw lines AC and CB.
Watch this video demonstrating the sum of angles of a triangle is 180 degree
