Banner 0
Banner 1
Banner 2
Banner 3
Banner 4
Banner 5
Banner 6
Banner 7
Banner 8
Banner 9

Q.

Question Image

If the angles of elevation of the top of the candle from two coins distant ‘a' cm and ‘b’ cm (a>b) from its base and in the same straight line from it are 30˚ and 60˚, then find the height of the candle.


see full answer

Your Exam Success, Personally Taken Care Of

1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.
An Intiative by Sri Chaitanya

a

ab cm

b

ab  cm  

c

a b  cm  

d

b a  cm   

answer is B.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

JEE

NEET

NEET

Foundation JEE

Foundation JEE

Foundation NEET

Foundation NEET

CBSE

CBSE

Detailed Solution

Given that, the angles of elevation of the top of the candle from two coins distant ‘a' cm and ‘b’ cm (a>b) from its base and in the same straight line from it are 30˚ and 60˚.
Let the candle be AB and the coins C, D are at a distance of ‘a’ cm and ‘b’ cm respectively from base B.
Consider the following figure, based on the given information.
Question ImageLet us assume, BD=a and BC = b  .
We can observe that, in ΔABD   tan 30 ° = h a   .
But,
1 3 =h/a h = a 3 ..[1]  
Let us find the height of the triangle.
In ΔABC  ,
tanC = CD BC tan 60 ° = h b 3 = h b h =b 3 .[2]  
Multiplying (1) and (2), we get,
  h×h = a 3 ×b 3 h 2 =ab h = ab  cm  
The height of the candle h= ab  cm  
The correct option is (2).
 
Watch 3-min video & get full concept clarity
score_test_img

courses

No courses found

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Get Expert Academic Guidance – Connect with a Counselor Today!

best study material, now at your finger tips!

  • promsvg

    live classes

  • promsvg

    progress tracking

  • promsvg

    24x7 mentored guidance

  • promsvg

    study plan analysis

download the app

gplay
mentor

Download the App

gplay
whats app icon
personalised 1:1 online tutoring