3, 7 sides inner angle and 900 degrees, outer angle and 360 degrees; 17 polygon, 360 degrees; 25 sides, 360 degrees.

4, 5 diagonals, 6 triangles, equal relationship

5,7 polygons, (900/7) degrees

6. Because angle 1= angle A+ 10, angle B=42, angle A+ angle 1,+angle B= 180, angle A=64, and angle A= angle ACD.

7. Let angle A=X, because angle C= angle ABC=2 angle A, angle C= angle ABC=2X, and because BD is perpendicular to AC, angle ABD=90-X, angle CBD=90-2X, angle ABD+ angle CBD= angle ABC, that is, (90-x)+(90-2x).

8. Because the angle BAC = 50, the angle C = 70 and the angle ABC = 60. Because AE and BF are bisectors, angle ABF-= 1/2, angle ABC = 30, angle BAE= 1/2, angle BAC = 25, so angle BOA = 65438+. Angle DAC=90- Angle C=20 degrees because AD is high.

9. Angle 1+ angle 2+ angle 3+ angle 4= 180- angle A=80 degrees, and because angle 1= angle 2, angle 3= angle 4, angle 2+ angle 4= angle 1+ angle 3 = 6544.

10, (1) BEcause be and CF are bisectors, angle ABE= angle EBC= 1/2 angle ABC, angle ACF= angle FCB= 1/2 angle ACB.

Angle BGC= 180- angle EBC- angle FCB= 180- (angle EBC+ angle FCB) = 180- (angle ABC+0/2+0/2+ACB) = 18.

(2) because angle ABC+ angle ACB= 180- angle a, because be and CF are bisectors, angle EBC+ angle FCB= 1/2 (angle ABC+ angle ACB)= 1/2( 180-)

1 1、