Upload
others
View
11
Download
0
Embed Size (px)
Citation preview
Unit: Angle RelationshipsStudent Handout 3
Name Answer Key
Date
ANGLE SUM
INTERIOR ANGLES OF TRIANGLES
We know that the sum angles in any
triangle always equals 1800
• Use what you know about parallel lines cut by a transversal to help you
prove this fact about the angle surn of triangles to be true.
PROOF l: Line A is parallel to Line B. Prove that the sum of the interior angles in Triangle CDE is 1800.
c
620 350BD
FACT EXPLAIN
Ll and LD are alternate interior angus620
350
- 83 0
and must be congruent.
and ZE cre alternate Interior anglesand must be congruent.
L 1, L2 and z?) must cdd up to 180line.because they form a straight
Conclusion: The sum of the interior angles in a triangle is 180 0 , because...By proving that angle 2measures 83 0, we can check the total sum of the angles in the triangle: 83 + 62 + 35 = 180.
PROOF 2: Line C is parallel to Line D. Lines E and F are transversals.
FACT EXPLAIN
C The three angles form a straight
1800line which equals 180.
z-2 and z4 are alternate interiorangles and must be congruent.
zl and L5 are correspondingangles and must be congruent.
Conclusion: The sum of the interior angles in a triangle is 1800 because...and we can replace L2 with /-4, and Ll with L5, then 7.3 + z4 + /-5 = 180.
OManeuvering the Middle LLC, 2016
Use what you know about angle relationships to answer the following questions.
I. Line C is parallel to Line D. What is the measure of /-5 if /-2 = 480 and L3 = 930. Explain howyou found your answer.
c48 0 L3
L4 48 0
We know that angle 2 and 4 are congruent
because they are alternate interior angles.
Angles 3, 4, cnd 5 must add uo to 180, 30angle 5 = 39 0
Use what you know about the sum of angles in a triangle to set up and solve an equation to find
the measure of each missing angle.
2. a. 13K -3 4.
6803x +
Equation: Equation: Equation:
4x —- 20
1
Iqx + 66= 180 8x -20= 1808x + ICC =
550 750 500
370 800
680 500350
5. In Triangle JKL, LK is 3 times the rneasure of a, and LI- is 8 times the measure of LJ. Find
the measure of each angle in Triangle JKL,
It's helpful for students to draw c picture:
150 450 1200
Summarize today's lesson:
OManeuvering the Middle LLC, 20 16