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# A2 Maths help!! C3 watch

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1. im doing this question on functions and I've gotten all the way through apart from the last last bit , this is C1 and C2 stuff but I cant figure out how to do it 😭
i need to find the gradient of y=-2cos(x) at the point (1,0)
honestly cant figure out how to do it any help would be much appreciated
thanks
2. (Original post by xoharrypotter)
im doing this question on functions and I've gotten all the way through apart from the last last bit , this is C1 and C2 stuff but I cant figure out how to do it 😭
i need to find the gradient of y=-2cos(x) at the point (1,0)
honestly cant figure out how to do it any help would be much appreciated
thanks
But the point (1,0) doesn't lie on that curve, so are you sure that you've written it right?

However, the method is simple: just differentiate and plug in the x-value.
3. (Original post by Indeterminate)
But the point (1,0) doesn't lie on that curve, so are you sure that you've written it right?

However, the method is simple: just differentiate and plug in the x-value.
turns out i needed to find the gradient of the inverse function thus: inversesin (1-x/2) im really confused on how that is only 1 mark I must be doing something wrong...

i have uploaded a picture of the whole question im stuck on the last part (question 3 (iii) the hence part)
4. (Original post by xoharrypotter)
turns out i needed to find the gradient of the inverse function thus: inversesin (1-x/2) im really confused on how that is only 1 mark I must be doing something wrong...

i have uploaded a picture of the whole question im stuck on the last part (question 3 (iii) the hence part)
Why would you find dx/dy when you can just find dy/dx and substitute x value in. But if you did have to find dx/dy remember that dy/dx = 1 / dy/dx

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