Constructions and Tilings | FIO

Question 12

Construct the following figure.

How do we construct the petals so that they are of the maximum possible size within a given square?

Question diagram 1
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Solution

We will draw a square, find the midpoints of its sides, and then draw arcs from the corners to form the petals.

Step 1 — Draw the square

Let us choose a side length for our square. Draw a straight line segment. Mark points A and B on this line. At point A, draw a line perpendicular to AB. Mark point D on this perpendicular line. Make sure the length AD is equal to AB. At point B, draw another line perpendicular to AB. Mark point C on this line. Make sure the length BC is equal to AB. Finally, join points C and D with a straight line. We have now drawn our square, ABCD.

Diagram 1

Step 2 — Find the midpoints of the sides

We need to find the middle point of each side of the square. Use a compass to find the perpendicular bisector of side AB. The point where it crosses AB is the midpoint. Let us call it P. Similarly, find the midpoint of side BC. Let us call it Q. Find the midpoint of side CD. Let us call it R. Find the midpoint of side DA. Let us call it S. These four midpoints are where the petals will touch the sides of the square.

Diagram 2

Step 3 — Draw the petals

Now we will draw the arcs that form the petals. Each petal is made of two curved lines, or arcs. There are four petals, so we will draw eight arcs in total.

For the top-left petal (near corner A): Place your compass needle at point D (bottom-left corner). Open the compass so its pencil tip is at point P (midpoint of AB). Draw an arc that starts at P and ends at point S (midpoint of DA). Now, place the compass needle at point B (top-right corner). Open the compass so its pencil tip is at point S. Draw an arc that starts at S and ends at point P.

For the top-right petal (near corner B): Place your compass needle at point A (top-left corner). Open the compass so its pencil tip is at point Q (midpoint of BC). Draw an arc that starts at P and ends at point Q. Now, place the compass needle at point C (bottom-right corner). Open the compass so its pencil tip is at point P. Draw an arc that starts at Q and ends at point P.

For the bottom-right petal (near corner C): Place your compass needle at point B (top-right corner). Open the compass so its pencil tip is at point R (midpoint of CD). Draw an arc that starts at Q and ends at point R. Now, place the compass needle at point D (bottom-left corner). Open the compass so its pencil tip is at point Q. Draw an arc that starts at R and ends at point Q.

For the bottom-left petal (near corner D): Place your compass needle at point C (bottom-right corner). Open the compass so its pencil tip is at point S (midpoint of DA). Draw an arc that starts at R and ends at point S. Now, place the compass needle at point A (top-left corner). Open the compass so its pencil tip is at point R. Draw an arc that starts at S and ends at point R.

You have now drawn all four petals. Erase any extra lines or marks if you wish. This is the required figure with four petals of maximum possible size within the square.

Diagram 3

More questions in FIO

Q1

When constructing the perpendicular bisector, is it necessary to have the same radius for the arcs above and below XY? Explore this through construction, and then justify your answer.

[Hint 1: Any point that is of the same distance from X and Y lies on the perpendicular bisector.

Hint 2: We can draw the whole line if any two of its points are known.]

Q2

Is it necessary to construct the pairs of arcs above and below XY? Instead, can we construct both the pairs of arcs on the same side of XY? Explore this through construction, and then justify your answer.

Q3

While constructing one pair of intersecting arcs, is it necessary that we use the same radii for both of them ? Explore this through construction, and then justify your answer.

Q4

Recreate this design using only a ruler and compass —

Q5

Justify why AB in Fig. 6.4 is the perpendicular bisector.

Q6

Can you think of different methods to construct a 90° angle at a given point on a line using a rope?

Q7

Construct at least 4 different angles. Draw their bisectors.

Q8

Construct the 8-petalled figure shown in Fig. 6.5.

Q9

In Step 2 of angle bisection, if arcs of equal radius are drawn on the other side, as shown in the figure, will the line OC still be an angle bisector? Explore this through construction, and then justify your answer.

Q10

What are the other angles that can be constructed using angle bisection? Can you construct 65.5° angle?

Q11

Come up with a method to construct the angle bisector using a rope.

Q12

Construct the following figure.

How do we construct the petals so that they are of the maximum possible size within a given square?

Q13

Construct at least 4 different angles in different orientations without taking any measurement. Make a copy of all these angles.

Q14

Construct the Fig. 6.6.

Q15

Construct 4 pairs of parallel lines in different orientations.

Q16

Construct the following figure.

Q17

Use support lines in Fig. 6.11 to construct a pointed arch. Make different arches, by changing the radius of the arcs.

Q18

Make your own arch designs.

Q19

Construct the following figures:

Q20

Optical Illusion: Do you notice anything interesting about the following figure? How does this happen? Recreate this in your notebook.

Q21

Construct this figure.

[Hint: Find the angles in this figure.]

Q22

Draw a line ll and mark a point P anywhere outside the line. Construct a perpendicular to the given line ll through P.

[Hint: Find a line segment on ll whose perpendicular bisector passes through P.]

Q23

How can the tangram pieces be rearranged to form each of the following figures?

Q24

Are the following tilings possible?

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