Two lines (x-3)/(1)=(y+1)/(3)=(z-6)/(-1) and (x+5)/(7)=(y-2)/(-6)=(z-3)/(4) intersect at the point R . The reflection of R in the xy -plane has coordinates :

3D Geometry: Two lines (x-3)/(1)=(y+1)/(3)=(z-6)/(-1) and… | JEE Main 2019

JEE Main 2019 (Online) 11th January Evening ShiftQuestion 1

Two lines $\frac{x-3}{1}=\frac{y+1}{3}=\frac{z-6}{-1}$ and $\frac{x+5}{7}=\frac{y-2}{-6}=\frac{z-3}{4}$ intersect at the point $R$. The reflection of $R$ in the $xy$-plane has coordinates :

3D Geometry

$(2,-4,-7)$✓ Correct answer$(2,4,7)$$(2,-4,7)$$(-2,4,7)$

Solution

Equating coordinates gives $s=-1$, $t=1$, so $R=(2,-4,7)$. Reflection in the $xy$-plane is $(2,-4,-7)$.

3D Geometry - JEE Mathematics question (JEE Main 2019 (Online) 11th January Evening Shift)

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