Question

An isosceles triangle has 2 angles of 65*. what is the other angle?

Answer 1

The sum of the angles of a triangle is 180°. x+ 65°+65°=180° /-130° x=50° ⇒ the 3rd angle is $50°$

Answer 2

$\angle \ a+ \angle \ b+ \angle \ c =180^0 \\\\ \angle a=\angle \ c=65^0 \\\\ 65^0+65^0+\angle \ b=180^0 \\\\ 130^0+\angle \ b=180^0 \\\\ \angle \ b=180^0-130^0 \\\\ \boxed{\angle \ b=50^0}$