S.chand publication New Learning Composite mathematics solution of class 7 Chapter 9 Pairs and Angles Exercise 9C

 Exercise 9C

Question 1

Using property of corresponding angles, find each of the lettered angles giving reasons.

Sol :

(a)=125° [corresponding ∠s, P||Q]

(b) a=40° [corresponding ∠s, l||m]

b=50°

(c) a=105° [corresponding ∠s, DC||AB]

Question 2

Using the properties of adjacent angles, vertically opposite angles and corresponding angles, fill in the size of each angle in diagram.

Sol :

(a)

∠1=(180°-50°)=130°

∴∠3=130°

∠4=50°

∴∠5=(180°-50°)=130°

∴∠6=50°

∴∠7=130°

(b)

∠1=(180°-110°)=70°

∴∠2=70°

∴∠3=110°

∠4=70°

∠5=110°

∠6=70°

∠7=110°

(c)

∠b=(180°-120°)=60°

∠a=(180°-135°)=45°

(d)

∠a=50°

∠b=(180°-40°)=140°

(e)

∠f=49°  ∴∠a=49°

∠e=75° ∴∠b=75°

∴∠d=(90°-49°)=56°

∴∠c=56°

(f)

∠p=360°-(145°+138°)

=360°-283°=77°