Find the solutions of the equation 3cos(2 theta) - 5cos(theta) + 2 = 0 in the interval 0 < theta < 2pi.

3cos^2(theta) - 3sin^2(theta) - 5cos(theta) + 2 = 0

3cos^2(theta) + 3cos^2(theta) - 3 - 5cos(theta) + 2 = 0

6cos^2(theta) - 5cos(theta) - 1 = 0

delta = 25 + 24 = 49

cos(theta) = (5 - 7)/12 = -1/6 or cos(theta) = 1

theta = 0 or arccos(-1/6) or 2pi - arccos(-1/6) or 2pi

PW
Answered by Piotr W. Maths tutor

4927 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Show that the determinant of the 3x3 matrix (2 1 1 / 2 1 7 / 6 3 5) is equal to zero.


Describe the set of transformations that will transformthe curve y=x^ to the curve y=x^2 + 4x - 1


What is exactly differentiation?


Use the chain rule to differentiate y=1/x^2-2x-1


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