Mathematics: Post your doubts here!

[***amd***]

I asked my friend answer, he also dont know but knows the direct answer, it is 585.2
and value is 20. Thats what he texted me. Not 24.

I got 20

 

[The Sarcastic Retard]

Well, I cant be 100 % sure here, but here's what I did.
Greatest value of cosine is 1. You will get that when 1/2(theta) is 360
greatest value of sin is also 1. You will get that when 1/2(theta) is 90
Therefore plugging in 1 will give you 7 plus 5 plus 12 which is 24
Now 24 is the greatest value that occurs. For the smallest 'positive' however, you need a positive sign will the largest number i.e. 12 and a negative sign with 5 to get the smallest value. Therefore 1-5 12 will give you 14.
For less working you can even use your answer to part i and then determine cos and sin values
I repeat I'm not sure if that's correct. That was my mental calculation

7+13cos(1/2@ + 67.38).
Maximum value is when cos(1/2@ + 67.38) = 1
so its 7 + 13 = 20. I know this.
Hope u got this

 

[The Sarcastic Retard]

I got 20

That is not what my doubt is.
The next part of the same question. that is what ma doubt is.
Thanks.

 

[Anum96]

7+13cos(1/2@ + 67.38).
Maximum value is when cos(1/2@ + 67.38) = 1
so its 7 + 13 = 20. I know this.
Hope u got this

Ohh, I just memorized the iii part and did it. Didnt bother reading the first 2
Sorry

 

[***amd***]

I asked my friend answer, he also dont know but knows the direct answer, it is 585.2
and value is 20. Thats what he texted me. Not 24.

to get greatest value of the whole expression, u need to have greatest value of "5 cos x - 12 sin x" (assuming x = 1/2 fi)
let y = cos x - 12 sin x

differentiate y,
dy/dx = -5 sin x - 12 cos x = 0 (to find the turning point)
solve...
x = 112.62, 292.62
one is minma, and one is maxima
one will give u max value of y, and one will give least

max y = 13, gives max of that expression 13 + 7 = 20
min y = -13, gives least value 7 - 13 = -6

 

[***amd***]

That is not what my doubt is.
The next part of the same question. that is what ma doubt is.
Thanks.

u mean third part, right?

 

[Anum96]

to get greatest value of the whole expression, u need to have greatest value of "5 cos x - 12 sin x" (assuming x = 1/2 fi)
let y = cos x - 12 sin x

differentiate y,
dy/dx = -5 sin x - 12 cos x = 0 (to find the turning point)
solve...
x = 112.62, 292.62
one is minma, and one is maxima
one will give u max value of y, and one will give least

max y = 13, gives max of that expression 13 + 7 = 20
min y = -13, gives least value 7 - 13 = -6

The question says least 'positive'

 

[***amd***]

The question says least 'positive'

least positive value of "Fi", which gives largest possible value of that expression.

to get greatest value of the whole expression, u need to have greatest value of "5 cos x - 12 sin x" (assuming x = 1/2 fi)
let y = cos x - 12 sin x

differentiate y,
dy/dx = -5 sin x - 12 cos x = 0 (to find the turning point)
solve...
x = 112.62, 292.62
one is minma, and one is maxima
one will give u max value of y, and one will give least

max y = 13, gives max of that expression 13 + 7 = 20
min y = -13, gives least value 7 - 13 = -6

292.62 is smallest positive value of x to give the largest value of that expression,
is i assumed x = 1/2 fi
fi = 2 x
least fi = 2 * least x
least +ve fi = 2 * 292.62 = 585.24

The Sarcastic Retard hope u get this

 

[Anum96]

least positive value of "Fi", which gives largest possible value of that expression.

292.62 is smallest positive value of x to give the largest value of that expression,
is i assumed x = 1/2 fi
fi = 2 x
least fi = 2 * least x
least +ve fi = 2 * 292.62 = 585.24

The Sarcastic Retard hope u get this

 

[The Sarcastic Retard]

least positive value of "Fi", which gives largest possible value of that expression.

292.62 is smallest positive value of x to give the largest value of that expression,
is i assumed x = 1/2 fi
fi = 2 x
least fi = 2 * least x
least +ve fi = 2 * 292.62 = 585.24

The Sarcastic Retard hope u get this

why 112.6 isnt smallest?

 

[***amd***]

lol what?

why 112.6 isnt smallest?

read the Q again, it asks for least value of fi, which gives the greatest value of that expression.
112.6 gives the smallest value of that expression.

 

[Anum96]

lol what?

Nothing. I dont even read the whole question properly. Its a straight 11 mark qs

 

[***amd***]

Nothing. I dont even read the whole question properly. Its a straight 11 mark qs

tbh, i didnt read the whole Q either, but that was probably coz we just were asked to do one part

 

[Anum96]

tbh, i didnt read the whole Q either, but that was probably just coz we just were asked to do one part

Yes, Apparently... Never doing a part alone again

 

[F.Z.M. 7]

F.Z.M. 7
"All" kinds of maths homework problems...

pahlay btata, maths p3 main yah link likh ata

 

[The Sarcastic Retard]

lol what?

read the Q again, it asks for least value of fi, which gives the greatest value of that expression.
112.6 gives the smallest value of that expression.

least positive value of "Fi", which gives largest possible value of that expression.

292.62 is smallest positive value of x to give the largest value of that expression,
is i assumed x = 1/2 fi
fi = 2 x
least fi = 2 * least x
least +ve fi = 2 * 292.62 = 585.24

The Sarcastic Retard hope u get this

You said 292.62 is smallest positive value, but 112.6 is the smallest positive value. No?
Isnt 112 smaller than 292?

 

[***amd***]

You said 292.62 is smallest positive value, but 112.6 is the smallest positive value. No?
Isnt 112 smaller than 292?

boy boy boy, read the Q again, it asks for "smallest positive value of fi which will give u the largest possible value of that whole expression"
x = 112.6 gives you 'smallest' value of that exp,
it is x = 292.62 for which occurs the max value of the expression.

 

[***amd***]

pahlay btata, maths p3 main yah link likh ata

no! i meant will this link work for 'those' Qs...

 

[The Sarcastic Retard]

boy boy boy, read the Q again, it asks for "smallest positive value of fi which will give u the largest possible value of that whole expression"
x = 112.6 gives you 'smallest' value of that exp,
it is x = 292.62 for which occurs the max value of the expression.

Wil never get this concept.
anyways thanks.

 

[Glory Hunter]

How to prepare for P6 in just a day?
Any Idea guys?