Q13 (2 Viewers)

[Rafy]

Share and discuss your solutions here

 

[cookeemonstah]

lol

 

[Nws m8]

lol

 

[TheOptimist]

roflmao

 

[narenkumar]

Can someone, tell how they did part a?

 

[Nws m8]

Can someone, tell how they did part a?

fuck you indian, it was the easiest question !

I got 4/9 . (3)^1/2

 

[SandyS1995]

Can someone, tell how they did part a?

ah i just subbed it into my calc, squared it then took the square root of that and simplified. not sure if its right but whatevs.

 

[TheOptimist]

you let whats inside the bracket=alpha or whatever, then you simplify, use a bit of pythagorean ratios, then you have double angle somewhere and then you simplify

 

[Nws m8]

ah i just subbed it into my calc, squared it then took the square root of that and simplified. not sure if its right but whatevs.

u let theta = cos inverse of whateevr

then u get sin 2 theta which equals 2 sin theta cos theta and fkin sub in values from cos theta= 2/3

 

[jennnnnnn]

fuck you indian, it was the easiest question !

I got 4/9 . (3)^1/2

... 4/9 (5)^1/2

 

[hsc2012la]

let inverse cos (2/3) = theta
draw up the triangle and find the other side which is root(5)
therefore it'll be sin(2theta -> since theta equals inverse of cos etc). Expand it into 2sinthetacostheta and then use the dimensions of the triangle, sub it in and you should get 2(root5/3)(2/3) = 4 root5/ 9

 

[Kieran95]

How do you do 13cii ?

 

[Nws m8]

... 4/9 (5)^1/2

yh typo, it was 5

 

[SandyS1995]

... 4/9 (5)^1/2

thats what i got!

 

[SandyS1995]

let inverse cos (2/3) = theta
draw up the triangle and find the other side which is root(5)
therefore it'll be sin(2theta -> since theta equals inverse of cos etc). Expand it into 2sinthetacostheta and then use the dimensions of the triangle, sub it in and you should get 2(root5/3)(2/3) = 4 root5/ 9

do u think ill lose a mark for straight subbing into calculator??

 

[Nws m8]

thats what i got!

same here

 

[Nooblet94]

Can someone, tell how they did part a?

Use the double angle formula to expand it and then draw up a right angled triangle with sides 2 and 3, find the 3rd side and use that to find sin(arccos(2/3))

 

[Nws m8]

do u think ill lose a mark for straight subbing into calculator??

yeah it was 2 marker

 

[megaman64]

... 4/9 (5)^1/2

yeh mee too

what did you guys get for 13.c.ii

 

[jennnnnnn]

Use the double angle formula to expand it and then draw up a right angled triangle with sides 2 and 3, find the 3rd side and use that to find sin(arccos(2/3))

i got 22hrs 46min for d)ii)