Question

4. find the angle of triangle ABC given that the lines A and B are parallel in figure 5.
This is the question of subject Math chapter lines and angles of standard 7.
​

Answer 1

Given :-

a  and  b  are parallel to each other

Need to find :-

the value of ∠ABC

Solution :-

let us take angles on line a

30° + ∠BAC + 50° = 180°  [ angles on same segment make 180° ]

∠BAC + 80° = 180°

∠BAC = 180° - 80°

∠BAC = 100°

let a be line XY

let  b  be line PQ

XY is parallel to PQ and let AB be the transversal.

∠XAB = 30°

so, ∠ABC = ∠XAB = 30°  [ alternate interior angles ]

∠BAC + ∠ABC + ∠BCA = 180° [ angle sum property ]

100° + 30° + ∠BCA = 180°

∠BCA = 180° - 130°

∠BCA = 50°

Conclusion :-

therefore, ∠BAC = 100°

∠ABC = 30°

∠CBA = 50°

Request :-

Please mark as brainliest if you are satisfied with the answer