URGENT HELP, COMPLEX NUMBERS, P3 Math!!!

[MW24595]

Salaam Walaikum,
I've been looking through the past papers and I found a question I didn't understand.
It was from May/June 2010 31 Question 7. Specifically the last part.
Here, You have to sketch the Argand Diagram. That's easy.
Next however, you've got to find the value of Mod Z for which the Argument is the lowest.
Now how the hell do you do that?
Logically, I tried drawing a tangent to the Circle on the Argand Diagram that would have the least argument. The tangent just touches the bottom of the circle and
so, makes the smallest possible angle with the x-axis for the values of z within the circle. But the tangent touches at point 2+i, which has a Modulus of Root 5.
The Mark Scheme says the Answer is Root 7. I don't understand, please help.
Thank You very much.
This is the link for the paper.
http://www.xtremepapers.com/CIE/Interna ... _qp_31.pdf

 

[mrpaudel]

Salaam Walaikum,
I've been looking through the past papers and I found a question I didn't understand.
It was from May/June 2010 31 Question 7. Specifically the last part.
Here, You have to sketch the Argand Diagram. That's easy.
Next however, you've got to find the value of Mod Z for which the Argument is the lowest.
Now how the hell do you do that?
Logically, I tried drawing a tangent to the Circle on the Argand Diagram that would have the least argument. The tangent just touches the bottom of the circle and
so, makes the smallest possible angle with the x-axis for the values of z within the circle. But the tangent touches at point 2+i, which has a Modulus of Root 5.
The Mark Scheme says the Answer is Root 7. I don't understand, please help.
Thank You very much.
This is the link for the paper.
http://www.xtremepapers.com/CIE/Interna ... _qp_31.pdf

The way u do is correct...!! i guess u did mistake somewhere..no worries buddy..try doing it a bit fairly..m sure, u will get it...i always used to do this way...! coz..doing graphically is a lot easier than solving them!!