17.* 1 point The radius of sphere 2x + 2y + 2z2 +x+y+ z = 0 is (a) 1/4 (b) 3/4 (c)v V3/4 (d) None of these O a O b O Od 5. 1 point Ifd is the distance between the centres of two intersecting sphers with radii T1,T2 and6 is the angle between the sphers then (a) cos = -d (b) cos @ = d+rfr 2 (d) Cos 0 = rj+r ) cos 2r (C)cos =ri 1'2