Question

A source of laser light sends rays AB and AC toward two opposite walls of a hall. The light rays strike the walls at points B and C, as shown below:

Answer 1

Let base of walls be D and E respectively

Now

• In∆AEC

$\\ \sf\longmapsto tan45°=\dfrac{80}{AE}$

$\\ \sf\longmapsto AE=\dfrac{80}{tan45}$

$\\ \sf\longmapsto AE=\dfrac{80}{1}$

$\\ \sf\longmapsto AE=80m$

• In ∆ADC

$\\ \sf\longmapsto cos60=\dfrac{AD}{40}$

$\\ \sf\longmapsto AD=0.5(40)$

$\\ \sf\longmapsto AD=20m$

Now distance between walls=

• AE+AD=80+20=100m

Answer 2

A source of laser light is at point A on the ground between two parallel walls. The walls are perpendicular to the ground. AB is a ray of light which strikes the wall on the left at point B which is 60 meters above the ground. AC is a ray of light which strikes the wall on the right at point C which is 40 m above the ground. The ray AB makes an angle of 60 degrees with the ground. The ray AC makes an angle of 30 degrees with the ground.