Design and Technology Topic
Circles and Polygons
- Read notes
- Flashcards
- Quiz
- Confident
Study focus - 3 things
- Regular polygons have equal sides and equal angles
- A circle can be used to construct regular polygons accurately
- Inscribed and circumscribed circles describe the relationship between a circle and a polygon
Section 1Regular polygons
A polygon is a closed plane shape with straight sides. A regular polygon has all sides equal and all angles equal. Examples include an equilateral triangle, square, regular pentagon, regular hexagon, and regular octagon.
Section 2Using a circle
A circle can help divide space evenly when constructing regular polygons. Marking equal divisions around the circumference and joining the points creates a regular polygon.
Section 3Inscribed polygons
A polygon is inscribed in a circle when all its vertices touch the circumference of the circle. The circle goes around the outside of the polygon.
Section 4Circumscribed circles and polygons
A circumscribed circle passes through all the vertices of a polygon. A polygon circumscribed about a circle surrounds the circle, with its sides touching the circle. Read the wording carefully.
Section 5Construction accuracy
Use a sharp compass point, keep the same radius when required, and mark points lightly before joining them. Check that equal sides look equal before darkening final lines.
Examples
Describe a regular hexagon constructed inside a circle.
The six vertices of the hexagon lie on the circumference, and the six sides are equal if the circle is divided evenly.
What does it mean if a triangle is inscribed in a circle?
All three vertices of the triangle touch the circumference of the circle.
Now let's water it
Session runs notes to flashcards to quiz back-to-back.