ECAT and MCAT Preparation: Post your doubts here!

[leadingguy]

Q. If a square prism is inscribed in a right circular cylinder of radius r and height h, the volume inside the cylinder but outside the prism is ....... ?

is the ans

r^3(pi/(2)^1/2 + 8)

 

[leadingguy]

some problems ....... rite here

1.)cos3x=?
a)4cos^3x - 3cosx
b)4cosx - 3cos^2x
c)4cos^2x - 3cosx
d)3cosx - 4cos^2x

2.)convert radian measure 4/(3.pi) to degree measure.
a)24.32
b)24.97
c)1.97
d)4.96

3.)tanx = ??
a) cosx + sinX
b) sinx/cosx
c) (2tan(x/2))(2tan(x/2)/1-tan^2(x/2))

4.)The area of rectangle ABCD is 48, and its peremiter is 28, then AB - Bc is??

a)Not possible
b)12
c)24
d)36

5.)sina =(3^1/2)/2
cosb =(1/(2^1/2))

now (a + b) = ??
a)110 degrees
b)105 degreees
c)100 degrees
d)90 degrees

most of the ans. are known to me but mine donot match the one in book so plz.. help out

 

[unique840]

some problems ....... rite here

1.)cos3x=?
a)4cos^3x - 3cosx
b)4cosx - 3cos^2x
c)4cos^2x - 3cosx
d)3cosx - 4cos^2x

2.)convert radian measure 4/(3.pi) to degree measure.
a)24.32
b)24.97
c)1.97
d)4.96

3.)tanx = ??
a) cosx + sinX
b) sinx/cosx
c) (2tan(x/2))(2tan(x/2)/1-tan^2(x/2))

4.)The area of rectangle ABCD is 48, and its peremiter is 28, then AB - Bc is??

a)Not possible
b)12
c)24
d)36

5.)sina =(3^1/2)/2
cosb =(1/(2^1/2))

now (a + b) = ??
a)110 degrees
b)105 degreees
c)100 degrees
d)90 degrees

most of the ans. are known to me but mine donot match the one in book so plz.. help out

4 ka ans kia hai?

 

[leadingguy]

4 ka ans kia hai?

not possible.... what do u say??? and wat abt rest??

 

[unique840]

not possible.... what do u say??? and wat abt rest??

rest ka baad main dekhungi.
and 4 is not possible
area = l*b
perimeter = 2(l+b)
lb=48
l=48/b

2(l+b) = 28
l+b = 14
replace l with 48/b
quadratic equation banegi. solve it
u will get 6 and 8
ab - bc means l - b
8-6 is 2

 

[leadingguy]

rest ka baad main dekhungi.
and 4 is not possible
area = l*b
perimeter = 2(l+b)
lb=48
l=48/b

2(l+b) = 28
l+b = 14
replace l with 48/b
quadratic equation banegi. solve it
u will get 6 and 8
ab - bc means l - b
8-6 is 2

han na tou value is present same is mine... but not given in options???? so shud i select not possible??

 

[unique840]

han na tou value is present same is mine... but not given in options???? so shud i select not possible??

obviously.

 

[unique840]

isnt it 3b?

 

[leadingguy]

isnt it 3b?

wel yes i marked same... fr 3 (option b) but book says it's c

 

[unique840]

and it is 2a?

 

[unique840]

if it is tanx and NOT tan2x thn b is correct.

 

[leadingguy]

and it is 2a?

sorry bt didnot gt u??? what 2a???

 

[unique840]

sorry bt didnot gt u??? what 2a???

2 ka ans a hai?

 

[leadingguy]

2 ka ans a hai?

g bilkul.... and sorry no problem in this question... wrote unexpectedly..

 

[unique840]

2 ka ans a hai?

and what abt 5 ka ans? it is 105?

 

[leadingguy]

and what abt 5 ka ans? it is 105?

yes explanation plz???

 

[unique840]

yes explanation plz???

sin inverse and cos inverse lo dono given values ka. u will get a and b respectively. add them.
u must remember some standard values of sin and cos and tan

 

[leadingguy]

sin inverse and cos inverse lo dono given values ka. u will get a and b respectively. add them.
u must remember some standard values of sin and cos and tan

oh well thanx.... i put so much tym on this question using double angle identity i.e sin(a+b)

as i didnot remember the values of sin-1.... til now used calculator.

 

[unique840]

oh well thanx.... i put so much tym on this question using double angle identity i.e sin(a+b)

as i didnot remember the values of sin-1.... til now used calculator.

dun b sad. be happy happy. sb set hoga iA

 

[smzimran]

(pi)(r)^2(h) - LxBxH

Too generalistic!
we have to substitute for l and b and h.

is the ans

r^3(pi/(2)^1/2 + 8)

wrong

we know height of square prism = height of cylinder
but we have to find base area of square
volume of square prism = base area * height