Triangles and Quadrilaterals

Understanding Triangles

Recognise the three types of triangles by their angles: acute (all angles less than 90 degrees), right-angled (one angle of 90 degrees), and obtuse (one angle more than 90 degrees).
Identify the three types of triangles by their sides: equilateral (all sides are equal), isosceles (two sides are equal) and scalene (no sides are equal).
Know that the angles in a triangle add up to 180 degrees and use this to calculate missing angles.

Be aware of the Pythagorean theorem which applies to right-angled triangles: The square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.
Remember and apply the base and height rule to calculate the area of a triangle: (base x height) ÷ 2.

Be familiar with the term quadrilateral, which means a polygon with four sides.
Classify quadrilaterals into specific types such as square, rectangle, trapezium, parallelogram, kite and rhombus.

Understand that all quadrilaterals have internal angles that add up to 360 degrees.
Apply the formula to find the area of a rectangle (base times height) and use this knowledge to find the area of other quadrilaterals.
Know the key properties of quadrilaterals such as parallel sides, equal angles and equal sides.

Recognise how triangles and quadrilaterals can be transformed through rotations, translations, reflections and enlargements.
Understand the properties of these shapes that are preserved under each transformation.
Be able to identify congruent and similar triangles and quadrilaterals by considering transformations.