M4TH5 SU<KS

(i)	if OA is perpendicular to OC then: OA∙OC = 0
		OA∙OC 	= 1*0 + 2p*q + q*(-2p)
			= 2pq - 2pq
			= 0
		∴OA is perpendicular to OC

(ii)	CA		= OA - OC
			= (i + 2pj + qk) - [-(4p²+q²)i + 2pj + qk]
			= (4p²+q²-1)i
	|CA|		= √(4p²+q²-1)²
			= 4p²+q²-1