Edexcel FP1 Thread - 20th May, 2016

Has anyone got a worked solution to question 15 please http://crashmaths.com/wp-content/uploads/2015/12/Complex-Numbers-Worksheet.pdf struggling to get my head around it! Thanks :smile:

Reply 323

Do you have the answer to the question?

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Reply 324

Original post by alfmeister

Do you have the answer to the question?

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No, unfortunately there's no mark scheme for these worksheets

Reply 325

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I have tried to work through but not sure if I have the right answer

Reply 326

Original post by alfmeister

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I have tried to work through but not sure if I have the right answer

Please could you post your working? :smile:

Reply 327

Original post by economicss

Has anyone got a worked solution to question 15 please http://crashmaths.com/wp-content/uploads/2015/12/Complex-Numbers-Worksheet.pdf struggling to get my head around it! Thanks :smile:

This question has added years on to me
so we know it is a parallelogram, therefore, i made some equations using these facts and modelling c as a=bi
OC=AB
OA=CB
OB^2+CA^2=2(OA^2+CB^2)

a^2 +b^2=160
84-5b=6a

i have put the equations in order in which i developed them from the facts

i used all these equations to get a is 4 and b is 12

sorry if my explanation is bad

(edited 7 years ago)

Reply 328

Original post by wania98

This question has added years on to me
so we know it is a parallelogram, therefore, i made some equations using these facts and modelling c as a=bi
OC=AB
OA=CB
CA=OB

a^2 +b^2=160
84-5b=6a
14b-4a=152

i have put the equations in order in which i developed them from the facts

i used all these equations to get a is 4 and b is 12

sorry if my explanation is bad

Haha I know how you feel! Where did you get the 160 from, did you use a sketch at all? :smile:

Struggling to visualise it!

Reply 329

Original post by economicss

Haha I know how you feel! Where did you get the 160 from, did you use a sketch at all? :smile:

Struggling to visualise it!

yh but my phone is out of battery
(AB)^2=(OC)^2

(AB)^2= (6-2)^2 +(5--7)^2
(AB)^2= 4^2 + 12^2
(AB)^2=160

(OC)^2=(a-o)^2+(b-0)^2
(OC)^2=a^2+b^2

Reply 330

I drew a diagram and found the displacement of point B from A. Then I knew that point C will be displayed the same distance from the origin as it is the opposite side of BA so I was able to deduce the coordinate of C.
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Reply 331

Original post by economicss

Haha I know how you feel! Where did you get the 160 from, did you use a sketch at all? :smile:

Struggling to visualise it!

Original post by wania98

...

\vec{OC} = \vec{AB} = 4 + 12i

Reply 332

Original post by alfmeister

5--7 = 5 +7 = 12 \neq 13

Reply 333

Original post by Zacken

5--7 = 5 +7 = 12 \neq 13

I think i got it wrong so embarrassed :bricks:

Reply 334

Original post by wania98

yh but my phone is out of battery
(AB)^2=(OC)^2

(AB)^2= (6-2)^2 +(5--7)^2
(AB)^2= 4^2 + 12^2
(AB)^2=160

(OC)^2=(a-o)^2+(b-0)^2
(OC)^2=a^2+b^2

i think im wrong sorry

Reply 335

Original post by wania98

i think im wrong sorry

You got

4 + 12i

as well, didn't you? It just looks like your method was a little contrived.

Reply 336

Original post by Zacken

You got

4 + 12i

as well, didn't you? It just looks like your method was a little contrived.

soz i thought you put b is 13 , night brain is kicking in

Reply 337

Oh yh silly mistake again, you can see my idea though. My bad again, sorry.

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Reply 338

Original post by alfmeister

Oh yh silly mistake again, you can see my idea though. My bad again, sorry.

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Yeah, I could see it was just a silly typo, only corrected you because I didn't want anybody to get confused. Don't apologise! :smile:

Reply 339