Download 1.4/1.5 notes

Name: __________________________ Date: ____________________
Geometry: Notes 1.4/1.5: Angles, their measures and bisectors
Angle:
Congruent angles:
A point is in the interior of an angle if it is
between points that lie on each side of the angle.
A point is in the exterior of an angle
if it is not on the angle or in its interior.
Angles Recap
Term
Measure
Sketch
Acute
Obtuse
Right
Straight
Two angles are ______________ if they share a common vertex and side, but have
no common interior points
Use a protractor. Measure and classify each angle.
1.
2.
3.
4.
Use the diagram below. Find the measure of each angle. Then classify the angle as acute, right,
obtuse, or straight.
4. mAFB
5. m AFD
6. m CFD
7. m BFD
8. m AFE
9. m BFE
10. m AFC
In the space below, draw an angle with the indicated measure.
11. 45o
12. 135o
13. 90o
Draw an angle that fits the description.
14. an obtuse angle, AFB
15. an acute angle, ABC
16. A straight angle, XYZ
Match each of the terms in the text box with its definition.
straight angle
obtuse angle
right angle
adjacent angle
acute angle
angle bisector
17. An angle whose measure is exactly 90o.
__________________
18. An angle whose measure is greater than 0o and less than 90o.
__________________
19. An angle whose measure is exactly 180o.
__________________
20. An angle whose measure is greater than 90o but less than 180o.
__________________
21. Two angles with a common vertex and a common side, but no common
interior points.
22. A ray that divides an angle into two congruent and adjacent angles.
___________________
__________________
ANGLE ADDITION POSTULATE:
If P is in the interior of RST , then
Examples:
23. If mFHI = 142, what are
mFHG and mGHI?
24. JKL is a right angle. What are
mJKM and mMKL?
BISECTING AN ANGLE
Angle bisector:
Draw and label a diagram of an angle bisector.
25. In the diagram, ⃗⃗⃗⃗⃗
𝐵𝐶 bisects ∠ABD. Find x.
26. In the diagram, XY bisects WXZ. Solve for x and find
mWXY.
27. ⃗⃗⃗⃗⃗
𝐵𝑇 bisects ∠ABC. Find the value of x and m∠ABC.
On a scale of one to ten, how comfortable are you with the following concepts?
_____ acute angle
_____ obtuse angle
_____ angle addition postulate
_____ right angle
_____ angle bisector
Check the website for tonight’s homefun assignment!
_____ straight angle