All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.
(i)
(ii)
(a)
Required answer
(b)
(iii)
KS Comments:
For (iib), students should draw the right angled triangle out to see what the value is since its required that they leave in exact form. When there is a circle for locus, I usually remind students to always utilise the radius.