Miscellaneous 3-D Problems
Three Dimensional Geometry

121423 If equation of the plane that contains the point \((-2,3,5)\) and is perpendicular to each of the planes \(2 x+4 y+5 z=8\) and \(3 x-2 y+3 z=5\) is \(\alpha x+\beta y+\gamma z+97=0\) then \(\alpha+\beta+\gamma=\)

1 18
2 17
3 16
4 15
Three Dimensional Geometry

121429 If \(P=(0,1,0), Q=(0,0,1)\), then the projection of \(P Q\) on the plane \(x+y+z=3\) is

1 2
2 \(\sqrt{2}\)
3 3
4 \(\sqrt{3}\)
Three Dimensional Geometry

121432 A variable plane \(\frac{x}{a}+\frac{y}{b}+\frac{z}{c}=1\), which is at a unit distance from the origin cuts the coordinate axes at \(A, B\) and \(C\). If the centroid \((x, y, z)\) of \(\triangle A B C\) satisfies \(\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2}=k\) then ' \(k\) ' equals

1 9
2 3
3 \(\frac{1}{9}\)
4 \(\frac{1}{3}\)
Three Dimensional Geometry

121436 If \(P=(0,1,2), Q=(4,-2,1), O=(0,0,0)\), then \(\angle \mathrm{POQ}\) is equal to.

1 \(\frac{\pi}{2}\)
2 \(\frac{\pi}{4}\)
3 \(\frac{\pi}{6}\)
4 \(\frac{\pi}{3}\)
Three Dimensional Geometry

121423 If equation of the plane that contains the point \((-2,3,5)\) and is perpendicular to each of the planes \(2 x+4 y+5 z=8\) and \(3 x-2 y+3 z=5\) is \(\alpha x+\beta y+\gamma z+97=0\) then \(\alpha+\beta+\gamma=\)

1 18
2 17
3 16
4 15
Three Dimensional Geometry

121429 If \(P=(0,1,0), Q=(0,0,1)\), then the projection of \(P Q\) on the plane \(x+y+z=3\) is

1 2
2 \(\sqrt{2}\)
3 3
4 \(\sqrt{3}\)
Three Dimensional Geometry

121432 A variable plane \(\frac{x}{a}+\frac{y}{b}+\frac{z}{c}=1\), which is at a unit distance from the origin cuts the coordinate axes at \(A, B\) and \(C\). If the centroid \((x, y, z)\) of \(\triangle A B C\) satisfies \(\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2}=k\) then ' \(k\) ' equals

1 9
2 3
3 \(\frac{1}{9}\)
4 \(\frac{1}{3}\)
Three Dimensional Geometry

121436 If \(P=(0,1,2), Q=(4,-2,1), O=(0,0,0)\), then \(\angle \mathrm{POQ}\) is equal to.

1 \(\frac{\pi}{2}\)
2 \(\frac{\pi}{4}\)
3 \(\frac{\pi}{6}\)
4 \(\frac{\pi}{3}\)
Three Dimensional Geometry

121423 If equation of the plane that contains the point \((-2,3,5)\) and is perpendicular to each of the planes \(2 x+4 y+5 z=8\) and \(3 x-2 y+3 z=5\) is \(\alpha x+\beta y+\gamma z+97=0\) then \(\alpha+\beta+\gamma=\)

1 18
2 17
3 16
4 15
Three Dimensional Geometry

121429 If \(P=(0,1,0), Q=(0,0,1)\), then the projection of \(P Q\) on the plane \(x+y+z=3\) is

1 2
2 \(\sqrt{2}\)
3 3
4 \(\sqrt{3}\)
Three Dimensional Geometry

121432 A variable plane \(\frac{x}{a}+\frac{y}{b}+\frac{z}{c}=1\), which is at a unit distance from the origin cuts the coordinate axes at \(A, B\) and \(C\). If the centroid \((x, y, z)\) of \(\triangle A B C\) satisfies \(\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2}=k\) then ' \(k\) ' equals

1 9
2 3
3 \(\frac{1}{9}\)
4 \(\frac{1}{3}\)
Three Dimensional Geometry

121436 If \(P=(0,1,2), Q=(4,-2,1), O=(0,0,0)\), then \(\angle \mathrm{POQ}\) is equal to.

1 \(\frac{\pi}{2}\)
2 \(\frac{\pi}{4}\)
3 \(\frac{\pi}{6}\)
4 \(\frac{\pi}{3}\)
Three Dimensional Geometry

121423 If equation of the plane that contains the point \((-2,3,5)\) and is perpendicular to each of the planes \(2 x+4 y+5 z=8\) and \(3 x-2 y+3 z=5\) is \(\alpha x+\beta y+\gamma z+97=0\) then \(\alpha+\beta+\gamma=\)

1 18
2 17
3 16
4 15
Three Dimensional Geometry

121429 If \(P=(0,1,0), Q=(0,0,1)\), then the projection of \(P Q\) on the plane \(x+y+z=3\) is

1 2
2 \(\sqrt{2}\)
3 3
4 \(\sqrt{3}\)
Three Dimensional Geometry

121432 A variable plane \(\frac{x}{a}+\frac{y}{b}+\frac{z}{c}=1\), which is at a unit distance from the origin cuts the coordinate axes at \(A, B\) and \(C\). If the centroid \((x, y, z)\) of \(\triangle A B C\) satisfies \(\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2}=k\) then ' \(k\) ' equals

1 9
2 3
3 \(\frac{1}{9}\)
4 \(\frac{1}{3}\)
Three Dimensional Geometry

121436 If \(P=(0,1,2), Q=(4,-2,1), O=(0,0,0)\), then \(\angle \mathrm{POQ}\) is equal to.

1 \(\frac{\pi}{2}\)
2 \(\frac{\pi}{4}\)
3 \(\frac{\pi}{6}\)
4 \(\frac{\pi}{3}\)