Diego bought 12 mini muffins for $4.20. how much would diego pay for 4 muffins? how many mini muffins could diego buy with $3.00?

Step-by-step explanation:

We need to prove that ,

We can start by taking RHS and will try to obtain the LHS . The RHS is ,

We know that , cos2A = 2cos²A - 1 ,

Simplify the bracket ,

Add the constants ,

Write each term in form of square of a number ,

Using (a+b)(a-b) = a² - b² , we have ,

This equals to LHS , therefore ,

Hence Proved !