2. 1.Angles are measured in Degrees 2.Acute Angle - Less than 90 o but greater than 0 o. 3.Right Angle - is 90 o 4.Obtuse Angle - greater than 90 o but less than 180 o. 5.Straight Angle - 180 o angle 6.Reflex Angle - Greater than 180 o but less than 360 o

3. Two angles are complementary angles if the sum of their measures is 90 o. Each angle is the complement of the other. Complementary angles can be adjacent or non adjacent. Adjacent Complementary angles. Non adjacent Complementary angles

4. Two angles are supplementary angles if the sum of their measures is 180 o. Each angle is the supplement of the other. Supplementary angles can be adjacent or non adjacent. Adjacent Supplementary angles. Non adjacent Supplementary angles

5. When two lines intersect, the opposite angles are equal. Angle 1 = Angle 2 Angle 3 = Angle 4 Sum of angles is 360 o Angle 1 and 3 are supplementary Angle 1 and 4 are supplementary Angle 2 and 3 are supplementary Angle 2 and 4 are supplementary

6. a)Complementary angles b)Supplementary angles c)Right angles d)Acute angles e)Obtuse angles f)Reflex angles g)Opposite angles Use the diagram to name the following angles Use the diagram to name the following angles.

7. Calculate the unknown angle measures. Calculate the unknown angle measures.. A) B)

8. A) B) 90 = x + 60 90 - 60 = x 30 = x 180 = 140 + (x - 30) 180 = 110 + x 180 - 110 = x 70 = x

9. Calculate the unknown angle measures. Calculate the unknown angle measures.. C) D)

10. C) D) 180 = x + 70 180 - 70 = x 110 = x y = 70 Because opposite angles 180 = y + 60 180 - 60 = y 120 = y 180 = 2x + 60 180 - 60 = 2x 120 = 2x 60 = x

11. Check solutions to Lesson 15(2) Copy notes to Lesson 16 Do Lesson 16 worksheet Check solutions when finished.