2-D shapes (age 10+)
Draw 2-D shapes using given dimensions and angles, using a ruler and protractor accurately
What a learner can do afterwards
- Draw a triangle with sides 5 cm, 7 cm and an included angle of 60°
- Construct a rectangle with given length and width using a ruler and set square
- Draw a regular pentagon given the side length and interior angle
1 · Read
You already know how to measure an angle with a protractor, and you know what makes a polygon regular or irregular. Now you put both skills to work: drawing a shape so it matches exact side lengths and angles, not just roughly the right shape.
To draw it: draw the 7 cm side first with your ruler. At one end, place your protractor on that line and mark 60°. Draw the 5 cm side from that mark. Join the two open ends, and the triangle is complete.
Keep your pencil point sharp so your ruler and protractor marks are exact. If one mark is even 1 mm or 1° off, the whole shape drifts by the time you draw the last side.
Measure carefully, mark each angle with your protractor, and draw each side to its exact length. That's how numbers become an accurate shape.
More to read
10.3 Triangles
Triangles are named by their sides and their angles. An equilateral triangle has three equal sides, an isosceles triangle has two, and a scalene triangle has none equal. To draw one accurately you need a ruler for the sides and a protractor for the angles. A triangle with sides 5 cm and 7 cm and a 60 degree angle between them is scalene, since all three sides differ.
10.4 Polygons, Perimeter, and Circumference
Polygons are flat shapes with straight sides. Rectangles have four right angles and opposite sides equal, so a ruler and a set square draw them well. A regular pentagon has five equal sides and five equal interior angles of 108 degrees. Perimeter is the distance around a shape: add every side. For a regular pentagon with side 4 cm, the perimeter is 5 times 4, which is 20 cm.
How to Draw a Parallelogram: A Step-by-Step Guide
A parallelogram has opposite sides parallel and equal. Start by drawing the base with a ruler. Then draw the slanted side at your chosen angle through one end of the base. Copy both sides to finish the shape: the top matches the base and the other slant matches its partner. Check with a set square that opposite sides look parallel before you ink the lines.
How to Construct a 60 Degrees Angle Using Compass and Ruler
A 60 degree angle is the classic compass construction. Draw a base line and put the compass point on its end. Draw an arc crossing the line, then keep the same compass width and draw a second arc from that crossing. The line from the end point through the spot where the arcs cross makes 60 degrees with the base. This exact angle appears in every equilateral triangle.
Explore more
2 · Watch
به انگلیسیTake it off screen
Where it sits
Learn first
Optional connections
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
18 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.