ExamGOAL
Books
1
Subjective

Locate the following points

(i) $(1,-1,3)$ (ii) $(-1,2,4)$ (iii) $(-2,-4,-7)$ (iv) $(-4,2,-5)$

Explanation

Given, coordinates are

(i) $(1,-1,3)$

(ii) $B(-1,2,4)$

(iii) $C(-2,-4,-7)$

(iv) $D(-4,2,-5)$

X-increment = Y-increment = Z-increment = 1

2
Subjective

Name the octant in which each of the following points lies.

(i) $(1,2,3$)

(ii) $(4,-2,3)$

(iii) $(4,-2,-5)$

(iv) $(4,2,-5)$

(v) $(-4,2,5)$

(iv) $(-3,-1,6)$

(vii) $(2,-4,-7)$

(viii) $(-4,2,-5)$.

Explanation

(i) Point $(1,2,3)$ lies in first quadrant.

(ii) $(4,-2,3)$ in fourth octant.

(iii) $(4,-2,-5)$ in eight octant.

(iv) $(4,2,-5)$ in fifth octant.

(v) $(-4,2,5)$ in second octant.

(vi) $(-3,-1,6)$ in third octant.

(vii) $(2,-4,-7)$ in eight octant.

(viii) $(-4,2,-5)$ in sixth octant.

3
Subjective

If $A, B, C$ be the feet of perpendiculars from a point $P$ on the $X, Y$ and $Z$-axes respectively, then find the coordinates of $A, B$ and $C$ in each of the following where the point $P$ is

(i) $\mathrm{A}(3,4,2)$

(ii) $B(-5,3,7)$

(iii) $C(4,-3,-5)$

Explanation

The coordinates of $A, B$ and $C$ are the following

(i) $A(3,0,0), B(0,4,0), C(0,0,2)$

(ii) $A(-5,0,0), B(0,3,0), C(0,0,7)$

(iii) $A(4,0,0), B(0,-3,0), C(0,0,-5)$

4
Subjective

If $A, B$, and $C$ be the feet of perpendiculars from a point $P$ on the $X Y, Y Z$ and $Z X$-planes respectively, then find the coordinates of $A, B$ and $C$ in each of the following where the point $P$ is

(i) $(3,4,5)$

(ii) $(-5,3,7)$

(iii) $(4,-3,-5)$

Explanation

We know that, on $X Y$-plane $z=0$, on $Y Z$-plane, $x=0$ and on $Z X$-plane, $y=0$. Thus, the coordinate of $A, B$ and $C$ are following

(i) $A(3,4,0), B(0,4,5), C(3,0,5)$

(ii) $A(-5,3,0), B(0,3,7), C(-5,0,7)$

(iii) $A(4,-3,0), B(0,-3,-5), C(4,0,-5)$

5
Subjective

How far apart are the points $(2,0,0)$ and $(-3,0,0)$ ?

Explanation

$$ \begin{aligned} &\text { Given points, } A(2,0,0) \text { and } B(-3,0,0)\\ &A B=\sqrt{(2+3)^2+0^2+0^2}=5 \end{aligned}$$