1. The problem statement, all variables and given/known data Linearise the following equation I(theta) = (I1 – I2 ) cos (2theta) + I2 where I1 and I2 are constants. 2. Relevant equations I(theta) = (I1 – I2 ) cos (2theta) + I2 3. The attempt at a solution Not sure how to linearise the cos(2theta). Have tried trig identities, would the best option be to take roots of both sides of the equation?