(A) |sin2x|+|cos2x|∈[1,√2]and|siny|∈[0,1]
so, equation is valid only
for |siny|=1and|sin2x|+|cos2x|=1
No. of values of y∈[−2π,2π]=4
No. of values of x∈[−2π,2π]=17
hencenumberoforderedpair=68
(B) f(x)>0⇒x2−18+a>0f(x)∈R
⇒(18)2−4a<0
a>81
henceleastintergralvalueofa=82
(C) ∴cos−1|cosx|isperiodicwithperiodπ
⇒80π∫0[cos−1|cosx|]dx=80π∫0cos−1|cosx|]dx
=80[1∫00.dx+π/2∫11.dx+π−1∫π−21.dx+π∫π−10.dx]
=80(π−2)
(D) TherequiredNumberofNumber=6n−2.5n+4n
∴thegivenexpressionis=(An+2Bn+Cn)
hence A=6,B=5,C=4
⇒(10A+2B+C)=10×6+2×5+4=74