3. Interior angle bisectors of △ABC at vertices B and C intersect at D. Find ∠BDC if ∠BAC=100 ∘ . 4. Find the degree measure of an exterior angle of a regular 15-gon. 5. Given △ABC, construct a common point of angle bisectors with a ruler and compass. Describe all steps of your construction from scratch. 6. Does there exist a triangle with side lengths 9, 5 , 12 ? 7. Formulate the Side-Angle-Side congruence rule.
