Measurement · JHS2 Mathematics

Lesson notes

Learning Objectives

Indicator: B8.3.2.1.3 - Use the Pythagorean theorem to solve problems on right-angled triangle.

By the end of the lesson, learners can:

Identify the hypotenuse and the two legs of a right-angled triangle.
Use the Pythagorean theorem (a² + b² = c²) to find the missing side of a right-angled triangle when two sides are known.
Apply the theorem to find the altitude of an isosceles triangle by first identifying the right-angled triangle hidden within it.
Solve multi-step problems that require splitting a figure into right-angled triangles to find unknown lengths.
Justify their chosen side lengths by explaining which side is the hypotenuse in each problem.

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Curriculum details

Strand: Geometry and Measurement (Strand 3)
Sub-strand: Measurement (3.2)
Content standard: B8.3.2.1 - Apply the Pythagoras theorem, the primary trigonometric ratios and the formulas for determining the area of a circle to solve real problems.
Indicator: B8.3.2.1.3 - Use the Pythagorean theorem to solve problems on right- angled triangle.
Suggested placement: Term 3, Week 3 (Week 27 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: Mathematics, Common Core Programme (JHS1-JHS3), 2023, p. 144
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

E.g.1 An isosceles triangle has equal sides, 6cm long and a base of 4cm long. Find the altitude of the triangle.
E.g.2 Find the length of each of the diagrams indicated below:

Wide black-and-white mathematical teaching visual is organised as a labelled teaching diagram with vertical... — A wide black-and-white mathematical teaching visual is organised as a labelled teaching diagram with vertical divisions. Visible labels, values, and notation include: 6cm; 10cm; 13; 9; A; 12.

(i) the length x
(ii) the length CB
(iii) the longer length