Eyes. How do you draw these eyes with a compass? (For a hint, go to the end of the chapter.)
Answer
Each eye is made of two arcs of the same radius, one bulging up and one bulging down, meeting at the two corners of the eye. A small filled circle in the middle is the pupil.
Steps of construction (one eye)
Draw a light horizontal helper line. Mark two points on it 4 cm apart — these are the two corners of the eye.
Take a radius of about 2.5 cm in the compass. Place the tip at a point B below the helper line, on the perpendicular through the middle, so that the pencil passes through both corners. Draw the arc — it bulges upwards and becomes the upper eyelid.
Keeping the same opening, place the tip at the point A above the line, exactly as far above as B was below. Draw the arc — it bulges downwards and becomes the lower eyelid.
Mark the mid-point of the eye and draw a small circle of radius 0.7 cm there. Fill it in — that is the pupil.
Repeat everything for the second eye, using the same helper line and the same compass openings, so that both eyes look alike.
One eye. The tip at B (below) draws the upper curve; the tip at A (above) draws the lower curve. A and B are equally far from the helper line, so the eye comes out symmetrical.
Why A is above and B is below: an arc bends away from the compass tip. To make a curve that arches upwards, the tip must be below it; to make one that sags downwards, the tip must be above. Keeping A and B at equal distances from the helper line makes the upper and lower curves mirror images — a symmetrical eye.
Tip: this may need a few trials. Draw the helper lines very lightly with a hard pencil so that you can rub them out at the end.
Q2.
Make other artwork of your choice with a ruler and a compass.
Answer
Here are some designs that use only a ruler and a compass. Try them in your notebook and colour them.
Six-petal flower (rangoli): draw a circle. Without changing the compass opening, put the tip anywhere on the circle and cut an arc; move the tip to the cut point and repeat. Six arcs go all the way round and make a flower.
Chain of circles: mark points on a straight line at equal distances and draw a circle of the same radius at each. Overlapping circles give a lovely chain.
Crescent moon: draw a circle, then draw a second circle of the same radius with its centre a little to one side. The part between the two curves is a crescent.
Leaf (vesica): draw two circles of the same radius, each passing through the other's centre. The common part is a leaf shape.
Rings of a target: keep the tip at one point and draw circles of radius 1 cm, 2 cm, 3 cm, 4 cm. Colour alternate rings.
Try This: the six-petal flower works because the radius of a circle can be stepped around it exactly six times. Count the arcs — you will always get 6, never 5 or 7.