Given x = 3sin(y/2), find dy/dx in terms of x, simplifying your answer.

The first step is to find dx/dy in terms of y, which when differentiating comes out as 3/2cos(y/2), so dy/dx in terms of y is the reciprocal of this.The next step is to eliminate the y dependent terms, which can be done one of two ways. One posssible method is to draw a diagram of a right angled triangle with an angle representing y/2 and using the relationship x = 3sin(y/2) to find cos(y/2) in terms of x using pythagoras and basic trigonometry. The other method that could be used is to utilise the trigonometric identity sin2(y/2) + cos2(y/2) = 1 and using 3sin(y/2) = x to find an expression for cos(y/2) in terms of x.Either method will give the same answer, the relationship cos(y/2) = 1/3(9-x2)1/2. The final step is then to substitute this into dy/dx to eliminate cos(y/2) and the final expression is then dy/dx = 2/(9-x2)1/2.

MA
Answered by Max A. Maths tutor

5731 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

How do I sketch a graph of a polynomial function?


A particle P is projected vertically upwards from a point 20m above the ground with velocity 18m/s, no external forces act on it other than gravity. What will its speed be right before it hits the ground? Give your answer to one decimal place.


Use Integration by parts to find ∫ xsin3x dx


What is the point of differentiation?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences