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If bx + cy = a,where a,b,c are of the same sign,be a line such that the area enclosed...

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user8235304 | Student, Grade 11 | Valedictorian

Posted June 20, 2013 at 7:32 AM via web

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If bx + cy = a,where a,b,c are of the same sign,be a line such that the area enclosed by the line and the axes of reference is 1/8 sq. unit then

A) b,a,c are in geometric progression.

B) b,2a,c are in geometric progression.

C) b,a/2,c are in arithmetic progression.

D) b,-2a,c are in geometric progression.


(More than one option is correct.)

Tagged with math, straight lines

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aruv | High School Teacher | Valedictorian

Posted June 20, 2013 at 8:00 AM (Answer #1)

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Your equation of line is

`bx+cy=a`

Sustitute  respectively y and x  are 0 ,to get  x and y interceps.

Thus

y=0 , `x=a/b`

and

x=0   `y=a/c`

Area of triangle formed by line and axes

=`(1/2)(a/b)(a/c)`    (i)

But

`(1/2)a^2/(bc)=1/8`       (given)

`4a^2=bc`

`(2a)^2=bc`

This implies  b,2a,c are geometric progression

Appropriate answer be B

D is ruled out because condition a,b,c are of the same sign.

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