Question

lines and angles of class 9. please tell me answer it's really important for exam​

Answer 1

since line l || m

angle lAC = 80° (corresponding angles)

angle lAC is exterior angle for ∆ ABC

angle lAC = < ACB + < ACB

< ABC + 45° = 80°

< ABC = 80° - 45°

< ABC = 35°

Answer 2

Answer:

Angle B = 55⁰

Step-by-step explanation:

Angle C=45°

Angle A=80⁰ (As we know m || l so, because of Alternate Interior Angle Property Angle A = 80°)

As, ABC is a triangle so,

Angle A + Angle B + Angle C = 180⁰ (Angle Sum Property of Triangle)

80 + Angle B + 45 = 180

125 + Angle B = 180

Angle B = 180 - 125

Angle B = 55⁰