An Introduction to 2-D Shape Slideshow 15, Mathematics Mr Richard Sasaki, Room 307

Objectives Recall names of certain elements of basic shapesRecall names of certain elements of basic shapes Recall formulae to find attributes to certain basic shapesRecall formulae to find attributes to certain basic shapes Apply these formulae to finding missing values for shapesApply these formulae to finding missing values for shapes

Square Rooting We need to have a brief look at how to square root. For shapes we only need to consider the positive root.

Two Dimensional Shapes Shapes that are flat are called 2D Shapes. We will learn about these in detail in Chapter 5. For now, we will use basic properties. Let’s review some shape names. Square Rectangle (Oblong) Triangle CircleParallelogram

Quadrilaterals Quadrilaterals are shapes with edges. 4 The examples we saw just now were the, the and the. square rectangle parallelogram The Square All lengths are equal and edges meet at 90 o.

Quadrilaterals The Rectangle A rectangle has parallel sides that are equal in length and edges meet at 90 o.

Quadrilaterals The Parallelogram A parallelogram has two pairs of parallel sides and two pairs of equal angles. There are of course other quadrilaterals. We will learn about them in Chapter 5.

Other Shapes The Triangle Triangles have three edges and three angles. The Circle Circles have 1 curved edge (or infinite edges).

Substitution There are of course many other shapes to look at in Chapter 5. Let’s try an example. Example An isosceles triangle has base 4cm and height 10cm. Calculate the area. Let’s label the values given on the triangle. Note: Area is measured in square units.

Answers – Very Easy / Easy No, we need its base and height or an angle. The square

Answers – Medium / Hard The parallelogram