Curriculum

Course: Mathematics — First Preparatory

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Curriculum

Mathematics — First Preparatory

Unit 1: Numbers

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Unit 2: Algebra

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Unit 3: Statistics

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Unit 4: Geometry

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Text lesson

Quadrilaterals

Mathematics — First Preparatory

Quadrilaterals

Worked examples

Worked examples

Comparison aspect	Main idea	Keywords
Example 1	In a quadrilateral three of the angles measure 95° 80° and 110°. Find the fourth angle	quadrilateralthreeanglesmeasure
Solution	The three angles add up to 285° so the fourth angle = 360 − 285 = 75°	threeanglesfourthangle
Example 2	In a parallelogram one angle is 65°. Find the other angles	parallelogramangleFindangles
Solution	The opposite angle is equal so it is 65°. The neighbouring angles are supplementary so each of them is 180 − 65 = 115°	oppositeangleequalneighbouring
Example 3	In a parallelogram two consecutive angles measure x and 2x. Find the four angles	parallelogramconsecutiveanglesmeasure
Solution	Their sum is 180 so 3x = 180 and x = 60. The angles are 60° 120° 60° and 120°	angles
Example 4	A rhombus has a side of 9 cm. Find its perimeter	rhombussideFindperimeter

Comparison aspect	Main idea	Keywords
Solution	All sides of a rhombus are equal so the perimeter = 4 × 9 = 36 cm	sidesrhombusequalperimeter
Example 5 (the hardest)	A rectangle is 12 cm long and 5 cm wide. Find its area and the length of its diagonal	rectanglelongwideFind
Solution	The area = 12 × 5 = 60 cm². In the right-angled triangle formed by the length the width and the diagonal Pythagoras’ theorem gives diagonal² = 12² + 5² = 144 + 25 = 169 so the diagonal = √169 = 13 cm	arearightangledtriangle

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