Geometry: An Interactive Journey to Mastery



Lesson 3: Angles and Pencil-Turning Mysteries

3. )LQGWKHPHDVXUHRIx and yLQHDFKRIWKHIROORZLQJ
   D௘ͽ
   20°
   30° x y

 E௘ͽ

32° 10°

y

x

F௘ͽ

20°

30°

y

80° x 80°

4. D௘ͽ ,VLWSRVVLEOHLQÀDWJHRPHWU\IRUDWULDQJOHWRKDYHDQREWXVHDQJOH",IVRVNHWFKVXFKDWULDQJOH
   ,IQRWZK\QRW"
   E௘ͽ ,VLWSRVVLEOHLQÀDWJHRPHWU\IRUDWULDQJOHWRKDYHWZRREWXVHDQJOHV",IVRVNHWFKVXFKDWULDQJOH
   ,IQRWZK\QRW"
   F௘ͽ ,VLWSRVVLEOHLQÀDWJHRPHWU\IRUDWULDQJOHWRKDYHWKUHHREWXVHDQJOHV",IVRVNHWFKVXFKDWULDQJOH
   ,IQRWZK\QRW"


5. )LOOLQWKHEODQNVRIWKHIROORZLQJSURRIͼ௘6HHFigure 3.6௘ͽ
   *LYHQ mIRY mIMY‘ ‘.
   Prove: ‘#‘GL.

Y

G

R

I

L M

Figure 3.

Figure 3.

Figure 3.

Figure 3.