Design and Technology Topic
Constructing Triangles and Quadrilaterals
- Read notes
- Flashcards
- Quiz
- Confident
Study focus - 3 things
- Accurate constructions depend on correct measurements, light construction lines, and sharp instruments
- Triangles can be constructed using side lengths, angles, or a mixture of sides and angles
- Quadrilaterals include squares, rectangles, parallelograms, rhombuses, and trapeziums
Section 1Construction accuracy
In technical drawing, constructions should be neat, accurate, and labelled. Use a sharp pencil, ruler, protractor, compass, and set squares. Draw construction lines lightly so final outlines stand out clearly.
Section 2Constructing triangles
A triangle can be constructed when enough information is given, such as three sides, two sides and an included angle, or one side and two angles. Begin with a clear base line, then use compass arcs or measured angles to locate the third point.
Section 3Types of triangles
An equilateral triangle has three equal sides, an isosceles triangle has two equal sides, and a scalene triangle has no equal sides. A right-angled triangle has one 90 degree angle.
Section 4Constructing quadrilaterals
A quadrilateral has four sides. Squares and rectangles need right angles. Parallelograms and rhombuses need opposite sides parallel. A trapezium has one pair of parallel sides.
Section 5Checking the drawing
After construction, check side lengths, angles, parallel lines, and labels. A small measurement error early in the construction can make the whole shape look wrong.
Examples
Construct an equilateral triangle with side length 6 cm.
Draw a 6 cm base. Set the compass to 6 cm and draw arcs from each end of the base. Join the arc intersection to both ends of the base.
What tools would help construct a rectangle 8 cm by 5 cm?
Use a ruler for the side lengths and a set square or protractor to form accurate right angles.
Now let's water it
Session runs notes to flashcards to quiz back-to-back.