Practical Geometry

Sponsor Area

Question
CBSEENMA8003149

Construct a quadrilateral ABCD when AB = 4 cm, BC = 6 cm, CD = 5 cm, AD = 5.5 cm and AC = 7 cm.

Solution

First of all make a rough sketch. Do not start construction without drawing a rough sketch showing sides, angles and diagonals, etc., with correct name.
Step I. Draw a rough sketch and mark the measurements.
Step II. Draw AC = 7 cm.
Step III. With A as centre and radius 4 cm, draw an arc above AC.
Step IV. With C as centre and radius 6 cm, draw another arc intersecting the previous arc at B.
Step V. With centre A and radius 5.5 cm, draw an arc below AC.
Step VI. With centre C and radius 5 cm, draw another arc to intersect the previous arc at D.
Step VII. Join DA and DC.


Thus, ABCD is the required quadrilateral.

Sponsor Area

Question
CBSEENMA8003150

Arshad has five measurements of a quadrilateral ABCD. These are AB = 5 cm, ∠A = 50°, AC = 4 cm, BD = 5 cm and AD = 6 cm. Can he construct a unique quadrilateral? Give reasons for your answer.

Solution

Solution not provided.

Question
CBSEENMA8003151

We saw that 5 measurements of a quadrilateral can determine a quadrilateral uniquely. Do you think any five measurements of the quadrilateral can do this?

Solution

No, any 5 measurements (elements) cannot determine a quadrilateral. Actually to construct a quadrilateral, we need a specific combination of measurements such as:

(a) Four sides and one diagonal.
or
(b) Three sides and two diagonals.
or
(c) Two adjacent sides and three angles.
or
(d) Three sides and two included angles.
or
(e) Some special properties are given.




Question
CBSEENMA8003152

Can you draw a parallelogram BATS where BA = 5 cm, AT = 6 cm and AS = 6.5 cm? Why?

Solution

Let us draw a rough sketch of BATS as given.
Here, we cannot locate the points T and B without knowing the measurements ST and SB respectively.
Thus, we cannot draw a parallelogram with the given measurements.