Common tangent qs

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praveen_84's picture
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In the showing diagram A and B are the centers of the two different Circle PQR is a common tangent points A, B and R lie on the straight line.


Distance between A and B is 25 cm and distance between P and Q is 24 cm. Diameter of the larger circle is 24 cm.

Q1. What is the ratio of AB:BR?
a. 7 : 5
b. 7 : 6
c. 7 : 10
d. data insufficient

Q2. what is the ratio of area triangle of APR and triangele BQR ?
a. 169 : 36
b. 144 : 25
c. 625 : 144
d. Cant be determined 

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jigar_er_civil's picture
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can u check data plz Little

can u check data plz

Little Star

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jigar_er_civil's picture
User offline. Last seen 2 years 37 weeks ago. Offline
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hey this is the

hey this is the approach...

1st consider as we know AB=25, PQ=24

this PQ is length of the tangent...for length of the tangent we have formula i.e., pq = sqrt(AB^2 - (R-r)^2)

we have R=12

then by substituting the values....we get...r= 5

let BR=x

the...we have...trngle APR and BQR are similar..... then..

AP/AR= BQ/BR

12/25+x = 5/x

x=125/7

then 1st question......

AB/BR= 25/(125/7) = 7/5 = 7:5

2nd question....

since APR BQR are similar.....  ratios of area of triangles= square of their corresponding sides.................

(ar trngle APR)/(ar trngle BQR)= (AP)^2/(BQ)^2 = 12^2/5^2= 144/25

ie.,144:25.............

Little Star

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