Mathematics: Post your doubts here!

[Saad the Paki]

my math teacher wrote sin90+x=cosx
cos(90+x)=-sinx
tan(90+x)=-1/tanx
is he right or he made a msitake!

He's right. It's the same as the one I've written

 

[osama ahmed ibrahim]

He's right. It's the same as the one I've written

do i have to memorise all of them
he also wrote sin360+x=sinx
cos360+x=cosx
tan360+x=tanx

 

[osama ahmed ibrahim]

.

 

[Saad the Paki]

do i have to memorise all of them
he also wrote sin360+x=sinx
cos360+x=cosx
tan360+x=tanx

I don't about the 360+x ones sorry
Well it's best if you do learn them

 

[Lola_sweet]

can someone explain this qs

 

[Rizwan Javed]

y = a/x = a x^-1

the volume is given by integrating πy^2. Here y is the equation of the line.
We're given Volume when rotated about x-axis is 24π.

24π = ∫ π (a * x^-1)^2 dx
24π = ∫ π (a^2 * x^-2) dx
24π = a^2 π ∫ (x^-2) dx
24 = a ^2 ∫ (x^-2) dx
Now integrate and put the limits:
24 = a^2 (1/3 - 1/1)
solve it to get:
a^2 = 36
=> a = 6 Ans.

 

[Lola_sweet]

y = a/x = a x^-1

the volume is given by integrating πy^2. Here y is the equation of the line.
We're given Volume when rotated about x-axis is 24π.

24π = ∫ π (a * x^-1)^2 dx
24π = ∫ π (a^2 * x^-2) dx
24π = a^2 π ∫ (x^-2) dx
24 = a ^2 ∫ (x^-2) dx
Now integrate and put the limits:
24 = a^2 (1/3 - 1/1)
solve it to get:
a^2 = 36
=> a = 6 Ans.

thank you

 

[farhan141]

9(ii) please with all steps. In part (i) the partial fractions are A=6, and Bx+C (B=-2)(C=1)

In Q.10 i need help in finding Alpha and Beta angles. Got P and Q.

 

[skyangel]

It can't be 88.2 cm! it's 33 cm.

thanks dear but in the marksheme its 88

 

[The Sarcastic Retard]

9(ii) please with all steps. In part (i) the partial fractions are A=6, and Bx+C (B=-2)(C=1)

In Q.10 i need help in finding Alpha and Beta angles. Got P and Q. View attachment 60356

not clearly coz no appropriate things to write on m enjoying vacations xD

 

[muhammadali233]

Does anybody have like a....Hard Q's compiled/List for P-1 and P-3?

 

[farhan141]

View attachment 60361
not clearly coz no appropriate things to write on m enjoying vacations xD

Buddy why didnt u multiply 6 with the first term binominal expansion?

 

[farhan141]

In denominator im getting (u-3)(u+2). Can anyone solve it and see if u r getting answer as shown.

 

[The Sarcastic Retard]

Buddy why didnt u multiply 6 with the first term binominal expansion?

coz 6 is in numerator. so 6(denominator)^-1

 

[farhan141]

coz 6 is in numerator. so 6(denominator)^-1

I dont think u cant completely ignore numerator.

 

[farhan141]

JLast part please.

 

[The Sarcastic Retard]

I dont think u cant completely ignore numerator.

Sorry?

 

[muhammadali233]

 

[farhan141]

Sorry?

6 is in numerator and u didnt multiply it after u expanded them?

 

[funky brat]

For part b why dont we use d sin theta over here?
Also if resistive forces were given will we use d or d sin theta?