Spot the expression that does not fit

Exercise and reference answers

Questions

1. Items

   1. cos 2x
   2. 1 - 2 sin^2 x
   3. 2 cos^2 x - 1
   4. 2 sin x cos x

   Odd item

   2 sin x cos x

2. Items

   1. sin x cos x
   2. sin 2x
   3. 2 sin x cos x
   4. sin(x + x)

   Odd item

   sin x cos x

3. Items

   1. sec^2 x
   2. 1 + cot^2 x
   3. 1 + tan^2 x
   4. 1/cos^2 x

   Odd item

   1 + cot^2 x

4. Items

   1. tan x
   2. sin x/cos x
   3. cot x
   4. 1/cot x

   Odd item

   cot x

Instructions

Tap the one expression that is not equal to the other three.

Explanation