abhas Active member
| Subject: Trinometry question [solved] Wed Aug 27, 2008 6:41 pm | |
| if 0<=x<=3pie , 0<=y<=3pie and cos x. sin y=1 the possible number.of ordered pair of (x,y) is cos x=cosecy -1<=cosx<=1 -1>=cosec y>=1 equality exists only when cosx=1,-1 and cosecy=1,-1 x=0,pi,2pi,3pi and y=pi/2,3pi/2,5pi/2 no of pairs(x,y)=3*4=12 WRONG anS ------------------------ SOLNS EXIST WEN cosx =1 and cosecy=1 ie x=0,2pi y=pi/2,5pi/2 =>4solns and wen cosx =-1 and cosecy=-1 ie x=pi,3pi y=3pi/2 =>2 solns in total 6 ans |
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