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# Geometry for CAT 2011

Hi Guys, Geometry, Algebra and Number system form the major chunk of our QA section for CAT. Proficiency in these three sections would definitely boost our Quants scores. Contents of Geometry 1\. Plane Geometry - Basics and Tri...
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SET-18

The three sides AB, BC and CA of a triangle ABC are 7 cm, 10 cm and 12 cm long respectively. AB is extended to D and AD = 28 cm. BC is extended to E and BE = 20 cm. CA is extended to F and CF = 36 cm. What is the ratio of the area of triangle ABC to the area of triangle DEF?

Figure attached

Is it 1:17 ??
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i think the answer for set 18 is 1:18 not 1:17.

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freakonomist Says
got 1:17 as the answer , use area = 0.5* a*b*sin(t)

how did you get the angle?
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Given the ball is 5 cm above the water level which means under the water the height of the ball is 10 cm.So the centre of the ball is under water and it is (7.5 - 5)cm i.e. 2.5 cm under the water. So applying simple pythagoras theorem, radius of the circular area will be sqrt of 7.5^2 - 2.5^2 = 5 root(2)

Thus circumference = 2pi*r = 10*pi*root(2)

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noma Says
Whats the answer not able to solve...

got 1:17 as the answer , use area = 0.5* a*b*sin(t)
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SET-18

The three sides AB, BC and CA of a triangle ABC are 7 cm, 10 cm and 12 cm long respectively. AB is extended to D and AD = 28 cm. BC is extended to E and BE = 20 cm. CA is extended to F and CF = 36 cm. What is the ratio of the area of triangle ABC to the area of triangle DEF?

Figure attached

Whats the answer not able to solve...
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Radius of the ball, OA = 5 root(5) (By Pythagorus theorem)

Circumference = 2*pi*r = 10 root(2)

Please mark your questions SET-wise, so that it would be easy to refer them. Thank you !

Please explain further not able to get why OA would be the new radius?
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a ball of diameter 15 cm is floating so that the top the ball is 5 cm above the smooth surface of the pond .what is the circumference in cm of the circle formed by the contact of the water surface with the ball.

plz sove this ques

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a ball of diameter 15 cm is floating so that the top the ball is 5 cm above the smooth surface of the pond .what is the circumference in cm of the circle formed by the contact of the water surface with the ball.

plz sove this ques

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a ball of diameter 15 cm is floating so that the top the ball is 5 cm above the smooth surface of the pond .what is the circumference in cm of the circle formed by the contact of the water surface with the ball.

plz sove this ques

Radius of the ball, OA = 5 root(5) (By Pythagorus theorem)

Circumference = 2*pi*r = 10 root(2)