CK-12 Geometry Concepts

1.6. Angle Classification http://www.ck12.org

1. Two angles always add up to be greater than 90◦.


2. 180◦is an obtuse angle.


3. 180◦is a straight angle.


4. Two perpendicular lines intersect to form four right angles.


5. A right angle and an acute angle make an obtuse angle.

For exercises 6-11, state what type of angle it is.

6. 55◦


7. 92◦


8. 178◦


9. 5◦


10. 120◦


11. 73◦


12. Interpret the picture to the right. Write down all equal angles, segments and if any lines are perpendicular.


13. Draw a picture with the following requirements.

am p;AB=BC=BD m^6 ABD= 90 ◦

am p;m^6 ABC=m^6 CBD A,B,CandDare coplanar

In 14 and 15, plot and sketch^6 ABC. Classify the angle. Write the coordinates of a point that lies in the interior of
the angle.

14.A( 5 ,− 3 ),B(− 3 ,− 1 ),C( 2 , 2 )

15.A(− 3 , 0 ),B( 1 , 3 ),C( 5 , 0 )