

x = a cos + b sin , and
putting the value of x and y in x2+y2
we get a2+b2
=> x2+y2 =a2+b2
which is quadratic in nature,
coefficient of x2 = coefficient of y2
and no term involving xy
hence its locus represents a circle
sin sin

on tossing a pair of dice total outcomes are 36
out of which getting a total of 8 have possiblities {(2,6),(6,2),(3,5),(5,3),(4,4)}=5
and from these 5 outcomes getting same no. on both dice is (4,4)=1
so, probability is 1/5