proof for the derivative of sin(x) is cos(x) (5 marks)

let f(x)=sin x f'(x) lim h-> 0 = ( sin(x+h) - sin(x))/h. f'(x) lim h-> 0 =( sin(x)cos(h) + cos(x)sin(h) - sin(x))/ h. f'(x) lim h-> 0=(sin(x)(cos(h)-1)/h + cos(x) (sin(h))/h. then as h tends to zero. (cos(h)-1)/h=0 and sin(h)/h =1. f'(x)= cos(x) QED

NP
Answered by Nicola P. Maths tutor

3430 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Factorise 6x^2 + 7x - 3=0


Differentiate 2cos(x)sin(x) with respect to x


Consider f(x)=a/(x-1)^2-1. For which a>1 is the triangle formed by (0,0) and the intersections of f(x) with the positive x- and y-axis isosceles?


y=7-2x^5. What's dy/dx?Find an equation for the tangent to the curve where x=1. Is itan increasing or decreasing function when x=-2?


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