Articles: tag
#Geometry
5 articles about Geometry.
Learning maths · 8 min read
Keep mixing up area and volume formulas? Group plane and solid formulas to remember them
Area and volume formulas are easy to confuse. It is usually not a memory problem but a failure to sort plane figures and solid figures separately. The common formulas are grouped below, with unit conversion and common mistakes explained, and worked examples showing how to choose a formula, substitute numbers and check the answer.
DSE revision · 9 min read
When to use the cosine rule: choose between the sine rule and the cosine rule from the given information
When solving a triangle, first check whether you are given two angles and one side, or two sides and the included angle. That tells you whether to use the sine rule or the cosine rule. This article gives a practical method for choosing the rule from the given information, with worked examples and common mistakes, for S4 to S6 students preparing for the HKDSE.
Learning maths · 8 min read
3D trigonometry: can't see which triangle to use? Three steps to extract the plane triangle
When doing 3D trigonometry questions, once the diagram is three-dimensional you don't know which triangle to use. This article sets out a practical set of steps: first find the right angles and known sides, then extract the plane triangles one at a time, and finally state the reason for each step. It also explains how to practise this 'extracting the diagram' skill when revising and with a tutor.
DSE revision · 6 min read
DSE Maths formulas to learn, topic by topic
The formulas you need for HKDSE Mathematics Compulsory Part, grouped by topic: quadratics, straight lines, sequences, mensuration, trigonometry and statistics.
Learning maths · 6 min read
Similar triangle reasons and how to write the proof
The three reasons for similar triangles in the Hong Kong syllabus, how to set out the proof line by line, three worked examples and the RHS and SSA traps.