Chapter 28: Introduction to 3D coordinate geometry – Exercise 28.1
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(i)
Ans.
All are positive. So octant is XOYZ
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(ii)
Ans.
X is negative and rest are positive, so octant is X’OYZ
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(iii)
Ans.
Y is negative and rest are positive, so octant is XOY’Z
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(iv)
Ans.
Z is negative and rest are positive, so octant is XOYZ’
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(v)
Ans.
X and Y are negative and Z is positive, so octant is X'OY'Z
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(vi)
Ans.
All are negative, so octant is X’OY’Z’
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(vii)
Ans.
Y and Z are negative, so octant is XOY’Z’
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.1(viii)
Ans.
X and Z are negative, so octant is X’OYZ’
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.2(i)
Ans.
YZ plane is x-axis, so sign of x will be changed. So answer is (2, 3, 4)
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.2(ii)
Ans.
XZ plane is y-axis, so sign of y will be changed. So answer is (-5, -4, -3)
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.2(iii)
Ans.
XY-plane is z-axis, so sign of Z will change. SO answer is (5, 2, 7)
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.2(iv)
Ans.
XZ plane is y-axis, so sign of Y will change, So answer is (-5. 0. 3)
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.2(v)
Ans.
XY plane is Z-axis, so sign of Z will change So Answer is (-4, 0, 0)
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.3
Ans.
Vertices of cube are
(1, 0, -1) (1, 0, 4) (1, -5, -1)
(1, -5, 4)(-4, 0, -1)(-4, -5, -4)
(-4, -5, -1) (4, 0, 4)(1, 0, 4)
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.4
Ans.
3 – (-2) = 5, |0, -5| = =5,| – 1 – 4| = 5
5, 5, 5 are lengths of edges
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.5
Ans.
5 – 3 = 2, 0 – (- 2) = 2, 5 – 2 = 3
2, 2, 3 are lengths of edges.
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.6
Ans.
Introduction to 3D coordinate geometry – Exercise – 28.1 – Q.7
Ans.
(-3, -2, -5) (-3, -2, 5) (3, -2. -5) (-3, 2, -5) (3, 2, 5) (3, 2, -5) (-3, 2, 5)