theorems

Question 1

adjacent angles on a straight line

Answer 1

the sum of the angles is 180

the angles are supplementary

Question 2

adjacent angles on a right angle

Answer 2

the sum of the angles is 90

the angles are complementary

Question 3

vertically opposite angles

Answer 3

equal X

Question 4

corresponding angles

Answer 4

when two parallel lines are cut by a third line the angles in the corresponding position are equal.

Question 5

alternate angles

Answer 5

when two parallel lines are cut by a third line the angles in alternate position are equal.

Question 6

co-interior angles

Answer 6

when two parallel lines are cut by a third line, the angles in co-interior position are supplementary (sum 180)

Question 7

angles of a triangle

Answer 7

sum 180

Question 8

exterior angle of a triangle

Answer 8

exterior angle = sum of opposite interiors

Question 9

isosceles triangle theorem

Answer 9

in an isosceles triangle:

• the base angles are equal
• the line joining the apex to the midpoint of the base bisects the vertical angle and meets the base in right angles.

Question 10

the converse of isosceles triangle theorem

Answer 10

• if a triangle has two equal angles => it is isosceles
• the angle bisector of the apex of an isosceles triangle bisects the base at right angles.
• the perpendicular bisector of the base of an isosceles triangles passes through its apex.