Chapter 1
Orienting Yourself: The Use of Coordinates
CBSE Class 9
Mathematics Solutions
Educart Mathematics class Class 9 NCERT Exemplar cover
Question:

Plot point Z(5,6)\mathrm{Z}(5, -6) on the Cartesian plane. Construct a right-angled triangle IZN\mathrm{IZN} and find the lengths of the three sides. (Comment: Answers may differ from person to person.)

Answer: Verified
Answer image

Since, ZZ lies in Quadrant IV.

From graph,

Z=(5,6)Z = (5, -6)

I=(5,0) (directly above Z)I = (5, 0) \text{ (directly above } Z)

N=(0,6) (directly right of Z)N = (0, -6) \text{ (directly right of } Z)

Angle at ZZ is between IZIZ (vertical) and ZNZN (horizontal), so it is 9090^\circ.

Side lengths:

IZ=(0)(6)=6 unitsIZ = |(0) - (-6)| = 6 \text{ units}

ZN=50=5 unitsZN = |5 - 0| = 5 \text{ units}

IN (hypotenuse)=52+62IN \text{ (hypotenuse)} = \sqrt{5^2 + 6^2}

=25+36=61 units.= \sqrt{25 + 36} = \sqrt{61} \text{ units.}

### Concept Applied

The distance between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is

(x2x1)2+(y2y1)2 obtained directly from the\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \text{ obtained directly from the}

Baudhāyana–Pythagoras theorem.

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