Hello,

I've got this question I've been labouring over.

From a previous question I found dy/dx to be 1 / (sinƟcos^3Ɵ).The parametric equations of a curve are : x = 1 + 2sin^2Ɵ, y = 4tanƟ.

Now it says

So what I did was first try get a value for x and y by plugging in π/4 in the parametric equations."Find the equation of the tangent to the curve at the point where Ɵ = π/4, giving your answer in the form y = mx + c.

x = 1 + (sin/4)^2

x = 1.00

y = 4tan(π/4)

y = 0.05

Then I put in π/4 into the dy/dx equation.

1 / (sinπ/4)((cosπ/4)^3)

= 72.95

Using the point-slope rule:

y - y1 = m(x - x1)

y - 0.05 = 72.95(x - 1)

y = 72.95x - 72.95 + 0.05

y = 72.95x + 73

According to the mark scheme, that is WAY off, as their answer is y = 4x - 4. Where did I go wrong? Sorry if this is in the wrong category.