prove that sum of the internal angles of triangle is 180•

1.	prove that sum of the internal angles of triangle is 180•
Answer» Given: angle1,angle 2,angle 3 are the angles of the triangle To prove: angle 1+angle 2+angle 3=180Proof: angle 5 +angle 1+angle 4=180 (eq 1)Angle 5 =angle 2(alternate interior angle)(eq2)Angle 4=angle3(alternate interior angles)(eq2)From eq 1and2Angle 2 +angle 1+angle3=180OrAngle 1+angle2+angle 3=180Hence proved

Discussion