Question

lim x=0 Cos ax -cos bx / cos cx - cos dx

Answer 1

Answer is in attachment

Answer 2

Answer:

Refer to the image attachment for the answer

Step-by-step explanation:

First we apply the identity of cos2x and convert the entire equation in the form of sin.

Next, we take 2 common out and cancel it.

Then we multiply both the numerator and denominator by the squares of bx/2, ax/2, cx/2 and dx/2 respectively as and when required as given in the solution.

As we know that sinx / x when

lim x->0 is 1, we we can cancel them out to make 1.

Next we open the squares of the remaining variables and cancel out 4 and x square from the remaining equation and get the last three steps mentioned in the last line.

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