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.

Answered by Max A. Maths tutor

5639 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

The function f(x) is defined by f(x) = 1 + 2 sin (3x), − π/ 6 ≤ x ≤ π/ 6 . You are given that this function has an inverse, f^ −1 (x). Find f^ −1 (x) and its domain


The second and fifth terms of a geometric series are 750 and -6 respectively. Find: (1) the common ratio; (2) the first term of the series; (3) the sum to infinity of the series


A curve has the equation y=3 + x^2 -2x^3. Find the two stationary points of this curve.


Find the derivative of e^3x


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