A curve has equations: x=2sin(t) and y=1-cos(2t). Find dy/dx at the point where t=pi/6

Since this question concerns parametric's, one may move to eliminate t from the equation to calculate dy/dx directly. However, in this case it is much easier to use the chain rule and realise that dy/dx=dy/dt*dt/dx=dy/dt/dx/dt. This is easier as both y and x are very simple to differentiate with respect to t and because the final part of the question involves substituting in a value of t. Differentiating y, the 1 disappears as it is a constant and the -cos(2t) goes to 2sin(2t) using the chain rule. X differentiates to 2cos(t). Using our chain rule from above, dy/dx=2sin(2t)/2cos(t). The 2s cancel. With our knowledge of the double angle formula sin(2t)=2sin(t)cos(t), leaving us with dy/dx=2sin(t)cos(t)/cos(t)=2sin(t). When t=pi/6 dy/dx=2sin(pi/6)=1.

CH
Answered by Cameron H. Maths tutor

5696 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

find the integral for xe^10x


How do I find the limit of a sequence that is expressed as a fraction?


Differentiate y=ln(x)+5x^2, and give the equation of the tangent at the point x=1


If x=-2,1,2 and the y intercept is y=-8 for y=ax^3+bx^2+cx+d, what is a, b, c and d


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning