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If A(1,2,3),B(4,5,7) ,C(-4,3,-6) and D(2,9,2) are four given points then find the angle between the lines AB and CD. |
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Answer» Correct Answer - `0^(@)` `vec(AB) =(p.v. of B) -(p.v.of A) =(4hat(i)+5hat(j)+7hat(k)) -(hat(i) +2hat(j)+3hat(k)) =(3hat(i)+3hat(j)+4hat(k))` `vec(CD) =(p.v.of D) -(p.v.of C) =(2hat(i) +9hat(j) +2hat(k))-(-4hat(i) +3hat(j)-6hat(k)) =(6hat(i) +6hat(j)+8hat(k))` `" cos " theta =(|vec(AB).vec(CD)|)/(|vec(AB).vec(CD)|) =((3xx6 +3 xx 6 + 4xx8))/((sqrt(9+9+16))(sqrt(36+36+64)))` `=(68)/(sqrt(34)xxsqrt(136))=(68)/(34xx2)=1` |
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