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Maths edexcel yr 2 trig chapter 7

https://imgur.com/a/S0eR55G

Can someone help me with part c and d please?

For part c I got the 50p for the share price but for the month I got the answer as June with T being 6.515… the answers at the back say the month is July but I don’t understand why.

For part d I set p equal to 100 and rearranged but got -.28… and am not sure what to. From my part b I can see the answer is June which is what the book says but am not sure how to show that.

Reply 1

mqb2766

for c) Im presuming 6.51 is right, but t=1 would be feb ...
d) youd get a solution every 2pi (in radians) and agree its june.

Reply 2

username79352

https://imgur.com/a/8m29l1i

For c) I let t=-1 when subbing into the share price to give me the minimum.

For d I don’t know how to prove it because when I do I end up with may though I know it is June.

I’m also stuck on part e if you could help me please

Reply 3

mqb2766

Original post

by saminasb3

https://imgur.com/a/8m29l1i
For c) I let t=-1 when subbing into the share price to give me the minimum.
For d I don’t know how to prove it because when I do I end up with may though I know it is June.
I’m also stuck on part e if you could help me please

I agree for c) so t=6.5 corresponds to which month? 0.5 is jan, 1.5 is feb, ...
Same hint for d) 5.5 is which month?

Dont know the question for e).

Reply 4

username79352

https://imgur.com/a/qXXxwG1 part e. The book give 2400 profit.

Reply 5

username79352

Original post

by mqb2766

I agree for c) so t=6.5 corresponds to which month? 0.5 is jan, 1.5 is feb, ...
Same hint for d) 5.5 is which month?
Dont know the question for e).

Could you explain please how you got 0.5 for the starting bit of jan? So how is jan .5<t<1.5 and why doesn’t it start from 0?

Reply 6

username79352

Original post

by saminasb3

Could you explain please how you got 0.5 for the starting bit of jan? So how is jan .5<t<1.5 and why doesn’t it start from 0?

Never mind I think I worked it out. Is it because of the translation of 0.5? I forgot to do my intervals if so.

Reply 7

mqb2766

Original post

by saminasb3

Never mind I think I worked it out. Is it because of the translation of 0.5? I forgot to do my intervals if so.

t is the time in months from jan 1st. So 0.xxx will be jan, 1.xxx will be feb, .... Obv read the defns carefully.

The .5 in the previuos posts was because a) the ans was ~ .5 b) its in the middle of the months.

(edited 1 year ago)

Reply 8

mqb2766

Original post

by saminasb3

https://imgur.com/a/qXXxwG1 part e. The book give 2400 profit.

The share price at t=0 is not 200p which you seem to assume?
Not checked the rest, but you should be able to sort it?

Reply 9

username79352

Yep I got 2401.31… thank you. Don’t know why I completely ignored the sin bit.

Reply 10

username79352

So 5.5 would be June and 6.51 July?

Reply 11

mqb2766

Original post

by saminasb3

So 5.5 would be June and 6.51 July?

Of course. t in [0,1) would be jan, in [1,2) would be feb ... Its easy to make mistakes with questions like this where the variable definition and units are carefully defined. You need to read them carefully.