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Help me on this GCSE AQA 9-1 exam question please

The diagram shows a sketch of the circle with the equation x^2 + y^2 =5
The y-coordinate of point A is -1
The tangent to the circle at A crosses the axes at B and C as shown
Find the area of triangle OBC.
Reply 2
Original post by kaaarrrreeeeenaa
The diagram shows a sketch of the circle with the equation x^2 + y^2 =5
The y-coordinate of point A is -1
The tangent to the circle at A crosses the axes at B and C as shown
Find the area of triangle OBC.

What have you tried? Please post your working.
i worked out the x coordinate of A which would be 2 i did this by substituting and got x= + or - 2 so i chose +2 as its not on the negative side than thats it
Reply 4
Original post by kaaarrrreeeeenaa
i worked out the x coordinate of A which would be 2 i did this by substituting and got x= + or - 2 so i chose +2 as its not on the negative side than thats it

Okay the next thing you have to do is find the equation of the tangent, which is a standard thing you need to know how to do for GCSE. Have you done it before?
i tried that but i haven't got the gradient as i only have one coordinate of the tangent
Reply 6
Original post by kaaarrrreeeeenaa
i tried that but i haven't got the gradient as i only have one coordinate of the tangent

But you just found the other one? So you know that the coordinates of A are (2, -1).
Original post by kaaarrrreeeeenaa
i tried that but i haven't got the gradient as i only have one coordinate of the tangent


technically if you know the coordinates of point A then you can find the equation of the tangent. This is because the question does not mention any translation which means that the centre of the circle is (0,0)
First of all, find the gradient using the coordinates of point A with the coordinates of the centre of the circle
ohh dont worry i got it now
y-y1=m(x-x1)
Reply 11
Original post by kaaarrrreeeeenaa
i tried that but i haven't got the gradient as i only have one coordinate of the tangent

It sounds to me that you don't know how to find the equation of a tangent. Try looking in your textbook or watch a video like this.
thanks guys
Original post by kaaarrrreeeeenaa
thanks guys


post your answer just to make sure that you get the right one

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