# Month: April 2015

## Geometry Sum | ABCD is a square. Prove in each case ∆APD ≅ ∆BPC | Find Angle DPC Angle PCD and Angle PCD |

ABCD is a square and APB is an equilateral triangle. Prove in each case: 1) 𢁪PD ≅ 𢁫PC 2) Find the angles of 𢁭PC Solution : First PartGiven �P = Equilateral triangleR.T.P.1) 𢁪PD ≅ 𢁫PC 2) Find 𢈍PC, ∠PDC and ∠PCD, Proof: In 𢁪PD and 𢁫PC AP = BP | Same side of…

## Sums of Speed Distance and Time Part 3 | Mathematics Class 8

Three sums of speed distance and time are discussed in the video. The sums are given here. 1. A train 150 m long passes a telegrah post in 15 seconds.Find:a) Speed of the train in km/hr. b) Time taken by it to pass a plateform of 150 m long.Watch Solution in the Video…

## Speed Distance and Time For Class 8 | Part 2 Mathematics | Relative Speed of Boat

In this video sums related to relative speed of boat in standstill water stream and in a water stream having speed in the same direction and also in the opposite direction have been discussed. Watch the video and comment below. If you have sum of boat and stream then post it in the comment box.…

## Theorem: Tangent and Radius of a Circle | are Perpendicular to Each Other.

Theorem :Tangent and radius of a circle are perpendicular to each other. Solution : Given: A circle with centre O. AB is the tangent to the circle at point B and OB is the radius of the circle.R.T.P. OB ⊥ AC Proof: 1. OB < OC || Since each point of the tangent other than…

## Theorem : The Angle in a Semi-Circle is a Right Angle

Theorem: The angle in a semicircle is a right angle Given : A circle with centre 0 with � at centre and � at the circumference of the circle . RT.P. : the angle in a semicircle is a right angle. ie : ∠ ACB= 90o Statements: 1 𢈊OB = 2� || angle at the…

## Theorem : Opposite Angles of a Cyclic Quadrilateral are Supplementary | Class 8

Theorem : Opposite Angles of a Cyclic Quadrilateral are Supplementary. Solution : Given: ABCD is a cyclic quadrilateral.R.T.P.(Require To Prove) 1. � + � = 1800 2. � + � = 1800 Construction : Join OB and OD Proof: 1. ∠ BOD = 2 ∠BAD || Angle at the centre of a circle is…

## Theorem | the angle subtended by an arc of a circle | at the centre is double the angle subtended by it at | any point on the remaining part of the circle

Theorem : A circle with centre O in which AB subtends 𢈊OB at centre and angle � at any point on the remaining part of the circle. R.T.P. – 𢈊OB = 2 x � Solution : Construction: Join CO and produce CO to point D . 1. In ∆AOC, OC = OA || Radii of…