A triangular prism. The rectangular sides are 2.5 millimeters by 8 millimeters, 8 millimeters by 6.5 millimeters, and 8 millimeters by 6 millimeters. The 2 triangular sides have a base of 2.5 millimeters and height of 6 millimeters. The triangular prism shown has triangular face(s) and lateral face(s). The area of one triangular face is mm2. The surface area of the triangular prism is mm2.

Given: ab ≅ cd and ad ≅ bc prove: abcd is a parallelogram. statements reasons 1. ab ≅ cd; ad ≅ bc 1. given 2. ac ≅ ac 2. reflexive property 3. △adc ≅ △cba 3. ? 4. ∠dac ≅ ∠bca; ∠acd ≅ ∠cab 4. cpctc 5. ∠dac and ∠bca are alt. int. ∠s; ∠acd and ∠cab are alt. int. ∠s 5. definition of alternate interior angles 6. ab ∥ cd; ad ∥ bc 6. converse of the alternate interior angles theorem 7. abcd is a parallelogram 7. definition of parallelogram what is the missing reason in step 3? triangle angle sum theorem sas congruency theorem sss congruency theorem cpctc