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# C4 Implicit differentiation watch

1. Help me with these questions pls.

1.) The normal to the curve at the point (2,1) meets the axes at the points P and Q. Given that O is the origin, show that the area of triangle OPQ is square units.

I've done so far:

+ 3y + 2y = 0[/latex]
=

Then:

Y-1 = (X-2)
7Y-8X= -9

2.) The curve C has parametric equation x=asect, y=btant. prove that . Find the eq. in the form y=px + q of the tangent to C at the point where t=.

Done so far:
2. Hi maltsheys, lets have a look at these questions

1.) Draw the line 7y - 8x = -9, it might be better to think about it in the form y = mx + c. You should see that there is a clear triangle between the origin, the point where it crosses the x-axis and where it crosses the y-axis. a little hint, the triangle is in the 4th quadrant. Now you know how to calculate the area of a triangle, 0.5 x base x height.

2.) Ok really think about the equation you have produced, its much simpler if you simply write the equation out in terms of sin(t) and cos(t) and cancel out.
3. done it.
4. More help pls.

1.) The parametric equations of a curve are . Show that stationary values occur on this curve when .

I've done = 2cosx + 2cos2x over -2sinx -2sin2x
x=theta

2.) A curve is given by parametric equations

a.) find the eq. of the tangent at the point
= I've got
Then:
54y + x = 27 (correct)

b.) The tangent at A intersects the curve at point B. Find the value of the parameter t at B.

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