A Level Maths exam question on circles

Today's exam question is on circles. The first part is pretty standard, the second part a bit more creative.
Enjoy!
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[@atrioxne]

I randomly found your channel again today and came here to thank you. I passed my alevels maths almost 2 years ago with a good grade. Thank you very very much, without you it would not have been possible. Please keep up the good work. Thanks again.

[@StarfishMaths]

Oh that's so lovely to hear!! Well done with your exams, delighted that this channel was a help. Thank you for taking the time to say such kind words 😊 All the best with your endeavours!

[@joshuawaters5746]

You can also use implicit differentiation for the gradient of l, which is quicker for me.

[@roantp9985]

isnt it bigger than and equal to? if the circle touches the axis isnt that still in one quadrant?

[@joshuawaters5746]

No, the axis is an asymptote.

[@glitchedout8079]

Amazing video, that last question is cruel!

[@rumbidzaimachumi7746]

wow part b blew my mind