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# FP2 watch

1. Could someone explain to me parts 'a' and 'c' to me please?
Attached Images

2. a) is pretty obvious from the diagram and the text and c) follows from b).

Show some working.
3. (Original post by Serendreamers)
Could someone explain to me parts 'a' and 'c' to me please?
for a, draw 2 rectangles.

Make one rectangle using the line Z2 as a diagonal, and another with Z1. With angles and Z1=Z2, you can determine the answer
4. (Original post by 2710)
for a, draw 2 rectangles.

Make one rectangle using the line Z2 as a diagonal, and another with Z1. With angles and Z1=Z2, you can determine the answer
Hello

I'm still really confused as to why z1=iz2
5. (Original post by Serendreamers)
Hello

I'm still really confused as to why z1=iz2
Did you draw the rectangles? Let arg(Z1) = x degrees say. Now try and label every other angle of the rectangle according to x.
6. (Original post by 2710)
Did you draw the rectangles? Let arg(Z1) = x degrees say. Now try and label every other angle of the rectangle according to x.
Is it simply that,

z2 = z1 * cis(pi/2)
z2 = i z1

???
7. I have attached a picture
Attached Images

8. (Original post by Serendreamers)
Is it simply that,

z2 = z1 * cis(pi/2)
z2 = i z1

???
In my picture, tell me what y and k are, in terms of x. And then what can you tell me about the triangles
9. (Original post by 2710)
In my picture, tell me what y and k are, in terms of x. And then what can you tell me about the triangles
k=x, y=(pi/2)-x and the triangles are congruent
10. (Original post by Serendreamers)
k=x, y=(pi/2)-x and the triangles are congruent
Yes, can you see where to go from there?
11. (Original post by 2710)
Yes, can you see where to go from there?
So, from the triangles and their angles, I can deduce that

z1 = a+bi and z2 = -b+ai

which confirms with the statement

iz1 = i(a+bi) = -b+ai = z2

Is this it?
12. (Original post by Serendreamers)
So, from the triangles and their angles, I can deduce that

z1 = a+bi and z2 = -b+ai

which confirms with the statement

iz1 = i(a+bi) = -b+ai = z2

Is this it?
yes
13. (Original post by 2710)
yes
Well, I have already thought of this as a solution but the mark scheme surprisingly did not give me 2/2 marks for this explanation

Is there another reason why iz1=z2? Unfortunately, the mark scheme isn't very helpful...
Attached Images

14. (Original post by Serendreamers)
Is it simply that,

z2 = z1 * cis(pi/2)
z2 = i z1

???
Did the markscheme not reward this?
15. (Original post by aznkid66)
Did the markscheme not reward this?
See my above post, it simply states 'Explantion' implying that the answer is very obvious
16. (Original post by Serendreamers)
See my above post, it simply states 'Explantion' implying that the answer is very obvious
Sorry, I missed that.

Anyway, I don't see what the problem is. The mark scheme rewards partials for both adding the angles and using congruent components, so either method written out fully should be sufficient. What do you mean by "the mark scheme did not give [you] 2/2 marks"?
17. (Original post by aznkid66)
Sorry, I missed that.

Anyway, I don't see what the problem is. The mark scheme rewards partials for both adding the angles and using congruent components, so either method written out fully should be sufficient. What do you mean by "the mark scheme did not give [you] 2/2 marks"?
Don't worry about it, I just got a bit confused

Do you have any idea for part 'c'?
18. I'm confused about "in terms of z1", but it should follow from the diagram you drew.

Do you know where else the perpendicular bisector of an isosceles triangle's unique side intersects the triangle?

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