Derive a formula for cos( in terms of and for all real numbers u

 (2α) = cos²(α) - sin²(α)

Step-by-step explanation:

The expression for cosine of the sum of two angles is:

cos (α + β) = cos(α)*cos(β) - sin(α)*sin(β)

in case α = β

cos ( α + α ) = cos (2α) = cos(α)*cos(α) - sin(α)*cos(α)

Hence cos (2α) = cos²(α) - sin²(α)

the answer is:

the correct option:

b.

to solve the problem, we need to remember how to operate to simplify exponential expressions using the logarithms.

we are given the equation:

then, using placing logarith with base 7 on both sides of the equation, we have:

so, rounding the obtained result to two decimal places (nearest hundreth), we have:

hence, we have that the correct option:

b.

have a nice day!