if angle c is a right angle and angle a equals 50 degrees , then prove that the measure of angle be equals 40 degrees . Which of the following would be the first step to assume in order to prove the statement above by contradiction using an indirect proof? Angle C is not a right angle. The measure of angle B does not equal 40 degrees. Angle C is a right angle. The measure of angle A equals 50 degrees. The measure of angle be equals 40 degrees