The density of gold is about how many times greater than the density of aluminum

according to Wikipedia:

Density of aluminum = 2.70 grams / cubic centimeter

Density of gold = 19.30 g / cc

19.30 / 2.70 = 7.1481481481 times denser

or rounded = 7.15 times denser

Step-by-step explanation:

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 !