After solving.. n came out to be 13.85.. and final ans is 14... I think it should be 13.. since it's about number of reflections so what I think it's that we cannot take approximations and approximate 13.85 to 14 ... Pls explain where am I thinking wrong..
muskan , 4 Years ago
Grade 12
1 Answers
Arun
Last Activity: 4 Years ago
here,
BC = 20cm
ABC = CBD = 30o
Now,
in triangle BCD
DC = BCtan30 = 20.tan30
thus,
DC = 20/√3cm
thus, the ray of light undergoes one reflection for every horizontal distance of 20/√3cm. The total distance covered to make all the reflections will be
now,
the number of reflections will be [length of mirror = 1.6m = 160cm]
= 160 / (20/√3)
~ 14 reflections
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