Question 1: Calculate the measure of an angle that is supplementary to a 110° co-interior angle.

Answer: 70

Question 2: If one co-interior angle measures 65°, what is the measure of its adjacent co-interior angle?

Answer: 115

Question 3: Two parallel lines are cut by a transversal. If one co-interior angle is 80°, what is the other co-interior angle?

Answer: 100

Question 4: Construct two parallel lines cut by a transversal such that one co-interior angle measures 120°. Calculate the other co-interior angle.

Answer: 60

Question 5: Plot on the grid: Draw two parallel lines cut by a transversal so that one co-interior angle is 130° and the adjacent is its supplementary angle.

Answer: 50

Question 6: A pair of co-interior angles are 75° and x°. Find x°.

Answer: 105

Question 7: In a real-world scenario, a road is cut by a railway crossing forming angles. If one co-interior angle measures 55°, what is the other?

Answer: 125

Question 8: Explain why co-interior angles formed by parallel lines are always supplementary.

Answer: Because when two lines are parallel, the angles on the same side of the transversal add up to 180° by the definition of supplementary angles.

Question 9: If one co-interior angle is 95°, what is its supplementary co-interior angle?

Answer: 85

Question 10: Identify the common mistake: A student says that co-interior angles are always equal. Is this correct? Explain your answer.

Answer: No, they are equal only if the angles are alternate interior angles. Co-interior angles are supplementary, not necessarily equal.

Question 11: Challenge: Two co-interior angles are 125° and x°. If the other two angles are equal, find x°.

Answer: 55