Grade 9 - Mensuration

Mensuration

(a) Formulae for area and perimeter of simple 2-D figures: triangle (including Hero’s formula for area), square, rhombus, rectangle, parallelogram and trapezium. Simple direct problems based on these including those involving inner and outer dimensions, cost.
(b) Formulae for surface area/total surface area and volume of 3-D solids: cube, cuboid and cylinder including problems of type involving:

Different internal and external dimensions of the solid.

Cost.

Concept of volume being equal to area of cross-section x height.

Open/closed cubes/cuboids/cylinders.

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Arithmetic
(a) Rational, irrational numbers as real numbers, their place in the number system. Surds and rationalization of surds.
(b) Irrational numbers as non-repeating, non- terminating decimals.

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Commercial Mathematics
Percentage
Simple Interest

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Algebra
(i) Expansions (a ± b)2 (a ± b)3 (x ± a)(x ± b)
(ii) Factorisation
a2– b2 a3 ± b3 ax2+ bx + c, by splitting the middle term.

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Geometry
(i) Angles formed at a point by two intersecting lines and parallel lines and a transversal Adjacent, supplementary, linear pair, vertically opposite, alternate, corresponding, allied (co-interior) and their properties.
(ii) Triangles

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Statistics
(i) Tabulation of raw data using tally-marks.
(ii) Understanding and recognition of raw, arrayed and grouped data.

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Trigonometry
(a) Trigonometric Ratios: sine, cosine, tangent of an angle and their reciprocals.
(b) Trigonometric ratios of standard angles- 0, 30, 45, 60, 90 degrees.

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Co-ordinate Geometry
(a) Dependent and independent variables.
(b) Ordered pairs, co-ordinates of points and plotting them in the Cartesian Plane.
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