FOR GMS ICSE 27TH AUG

Today we plan to follow up on our previous days work.

We shall be doing Ex/9(B) Nos. 1, 2, 3, 4, 9, 10, 12, 13, 14, 15, 16. Does it seem like quite a lot of work to do ? Please remember that we are doing class work and home work ! These are also the same types of sums and working at them together will help you to consolidate your learning - so kindly do them today !

Please note that you need, preferably, to work on graph paper. If you are at home and cannot go to a shop to buy graph paper because of the bandh - draw the graph using ruler and pencil.

In these sums we are

• again reflecting points in the X-axis, Y-axis and the point of Origin O (0,0), remember that when reflecting a point in the 
• X-axis, the sign of the ordinate (y coordinate changes), the abscissa remains the same.
• Y-axis, the sign of the abscissa (x-coordinate changes), the ordinate remains the same
• Origin O (0,0), the signs of both coordinates change.
• you will be asked to join some of the points you have plotted and be asked to name the triangle of quadrilateral. So let's revise this
• types of triangles 
• scalene (all the sides and angles are unequal and all angles are acute (less than 90 degrees)
• right angle triangle - a triangle in which one angle is a right angle (i.e. 90 degrees)
• an obtuse angle triangle - a triangle in which the sides and angles are unequal and one of the angles is more than 90 degrees
• an equilateral triangle - a triangle whose sides are equal and each angle is 60 degrees.
• an isosceles triangle - a triangle in which two sides are equal
• a right isosceles triangle - a right angle triangle in which the arms of the right angle are equal. The measure of the other angles are each 45 degrees
• types of quadrilaterals
• quadrilateral - a four sided figure in which all sides and angles are unequal.
• a parallelogram - a quadrilateral in which the opposite sides and opposite angles are equal and whose diagonals bisect each other.
• a square - a parallelogram in which all sides are equal and all the angles are right angles. The diagonals will be equal and bisect each other at right angles.
• a rhombus - a parallelogram in which all the sides are equal, whose diagonals bisect each other at right angles
• a rectangle - a parallelogram, in which all the anlges are right angles, The diagonals are equal to each other.
• a trapezium - a quadrilateral, one pair of whose sides are parallel 
• an isosceles trapezium - a trapezium whose non parallel sides are equal.
• you might also be asked to find the areas of the triangles or the quadrilaterals, so let's revise that :
• triangles
• area of a triangle = half x length of base x perpendicular height (to be used to finding the areas of right triangles or when you are given the base and the perpendicular height of the triangle from that base)
• area of a non right triangle the square root of s(s-a)(s-b)(s-c) where s = the sum of the sides divided by 3
• quadrilaterals
• remember that a diagonal of a quadrilateral divides the quadrilateral into two triangles and you can find the areas of the two triangles and them ad them to find the area of the quadrilateral
• area pf a square = side x side
• area of a rectangle = base x height
• area of a parallelogram - base x perpendicular height
• area of a rhombus = half the product of the diagonals
• area of a trapezium = half x (sum of parallel sides) x perpendicular height

All the best - off to work and remember that if you have any difficulty - I am only an e-mail away at broelmiranda@gmail.com