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# Math mechanics alevel question summer 2016 M2 52 watch

1. 9709/m/j/52/16
Anyone know how to do (ii)?

I got an answer for (i) which is 4 m. (−8 = 2x − x^2). I cannot do (ii). Below is the solution for (ii), but I don't understand it at all. How does tan^-1(2) come from? Does 2 come from 8/4 (Sy/Sx)? This does not seem correct to me.

Also, I am not sure how the picture of this should be looked like? Should it be like the left or the right one? From what I understand, I think it should be the one on the right. However, from the solution, it seems to be the left one that is correct.
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2. (Original post by anonymo007)
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For any function y=f(x), dy/dx is the tan of the angle that the curve makes with the +ve x-axis (up being positive).

So, in this case, dy/dx = 2-2x, which =2 when x=0.

So, tan of angle of projection = 2. Hence....

Also,dy/dx > 0 when x=0; so, the curve goes up initially.
3. (Original post by ghostwalker)
For any function y=f(x), dy/dx is the tan of the angle that the curve makes with the +ve x-axis (up being positive).

So, in this case, dy/dx = 2-2x, which =2 when x=0.

So, tan of angle of projection = 2. Hence....

Also,dy/dx > 0 when x=0 to the curve goes up initially.
You have made my day. Thank you so much

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