Show that 2tan(th) / (1+tan^2(th)) = sin(2th), where th = theta

We have 2tan(th) / (1 + tan^2(th)) = sin(2th)

We know that tan(A) = sin(A) / cos(A), and 1 + tan^2(A) = sec^2(A)

Therefore => (2sin(th) / cos(th)) / sec^2(th)

=> 2sin(th)*cos^2(th) / cos(th)

=> 2sin(th) cos(th)

=> sin(2th) by definition of trigonometric identities 

IC

Related Maths A Level answers

All answers ▸

y=4sin(kx) write down dy/dx.


The velocity of a car at time, ts^-1, during the first 20 s of its journey, is given by v = kt + 0.03t^2, where k is a constant. When t = 20 the acceleration of the car is 1.3ms^-2, what is the value of k?


Evaluate the integral ∫2x√(x^2 +1) dx


I don’t think I’m smart enough for this course, should I drop it?