Question

maths questionA straight line L1 passes through the point (3

Answer 1

For line L1 passes through the point (3,6,1) and is parallel to 2i+3j-k,

suppose L1:2i+3j-k=c ,

then 2*3+2*6-1=c ; c=17,

so L1:2i+3j-k=17.

suppose L2 :i-2j+k=c1,

so L2 :i-2j+k=9.

a) For the acute angle between L1 and L2 equals the acute angle between 2i+3j-k=0 (K1)and i-2j+k=0(K2),

then tanA=|K1-K2|/|1+K1K2|=sqr（42）/4,

so A=Arctan【sqr（42）/4】.

b） For the point B(5,a,b)lies on the line L2,

then 5-2a+b=9,

so 2a-b=-4.