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:

What is the distance between the walls?

100m
110m
50m
70m

Answer 1

\[\frac{ AB }{ AE } = \tan45^0\]
\[\frac{ EC }{ DE } = \tan60^0\]

Answer 2

AE + DE = distance between walls

Answer 3

so i add the tan of 45 and 60?

Answer 4

Nopes. See AE = AB/tan 45
and DE = EC/tan 60
you have the values for AE,EC, tan 45 and tan 60. you can find AE,DE

Answer 5

how do i find it? i dont get it

Answer 6

\[AE = \frac{ AB }{ \tan 45^0 }\]
\[AE = \frac{ 30m }{ 1 }\]
because tan 45 = 1

so what will be DE?

Answer 7

1.7?

Answer 8

correct..
now add both values

Answer 9

i add 1 and 1.7? i get 2.7

Answer 10

AE = 30
and DE = 1.7
so AE + DE = 30 + 1.7 = 31.7 m

Answer 11

ok then what?

Answer 12

hello?

Answer 13

wait I got it wrong somewhere. Please let me check

Answer 14

In right angle triangle EAB,
angle E + angle A + angle B = 180 degree
45 + 90 + x = 180
x = 45

Now as we know
\[\frac{ Opposite }{ Adjacent } = \tan \theta \]
\[\frac{ AE }{ AB } = \tan 45^0 \]
\[\frac{ AE }{ 30 } = 1\]
\[AE = \frac{ 30 }{ 1 }\]
\[AE = 30\]