Calculus/numerical

Advertisement


Question
sin form
sin form  
from image,can you plz tell me what happened to the step just next to the form. 2sin^2(theta)=1-cos2(theta),

Answer
Hi Muhammad,
From the sum of angle formula;
cos(A+B) = cosAcosB - sinAsinB
Letting A = B = θ
cos(2θ) = cosēθ - sinēθ

But we also know the identity; cosēθ + sinēθ = 1
and so
cos(2θ) = (1 - sinēθ) - sinēθ
2sinēθ = 1 - cos(2θ)

Hope that was what you were looking for.

Regards

Calculus

All Answers


Answers by Expert:


Ask Experts

Volunteer


Ahmed Salami

Expertise

I can provide good answers to questions dealing in almost all of mathematics especially from A`Level downwards. I believe i would be very helpful in calculus and can as well help a good deal in Physics with most emphasis directed towards mechanics.

Experience

Aspiring theoretical physicist. I have been doing maths and physics all my life.

Education/Credentials
I teach mathematics and engineering physics.

©2016 About.com. All rights reserved.