Question

Class 9th p please solve​

Answer 1

Answer:

First, draw two lines BE and CF such that BE ⊥ PQ and CF ⊥ RS.

Now, since PQ RS,

So, BE CF

We know that,

Angle of incidence = Angle of reflection (By the law of reflection)

So,

1 = 2 and

3 = 4

We also know that alternate interior angles are equal. Here, BE ⊥ CF and the transversal line BC cuts them at B and C

So, 2 = 3 (As they are alternate interior angles)

Now, 1 +2 = 3 +4

Or, ABC = DCB

So, AB CD alternate interior angles are equal)

Hope it helps u..

Answer 2

Answer:

To prove:- AB parallel to CD

Solution:-

Note:-

According to Physics,we know

Angle of Incidence= Angle of Reflection

Now, let's get into the solution

First we've to construct line BE perpendicular to PQ and line CF perpendicular to RS

also mark angle 1,2,3,4

For proving two lines are parallel

we've to prove their alternate interior angles are equal

as given PQ parallel to RS

If PQ parallel to PS

from the given attachment

angle 1= angle 2 (angle of Reflection= angle of incidence)

angle 3=angle 4 (angle of Reflection= angle of incidence)

Also BE parallel to CF

as we drawn

then

angle 2= angle 3(alternate interior)

if so, then

angle 1=angle 2=angle 3=angle 4

angle 1+angle 2=angle 3+angle 4

So, we've proved the alternate interior angles are equal, therefore

AB parallel to CD

Hence proved