Given:

To find:
The exact value of cos 15°.
Solution:

Using half-angle identity:


Using the trigonometric identity: 

Let us first solve the fraction in the numerator.

Using fraction rule: 

Apply radical rule: ![\sqrt[n]{\frac{a}{b}}=\frac{\sqrt[n]{a}}{\sqrt[n]{b}}](https://tex.z-dn.net/?f=%5Csqrt%5Bn%5D%7B%5Cfrac%7Ba%7D%7Bb%7D%7D%3D%5Cfrac%7B%5Csqrt%5Bn%5D%7Ba%7D%7D%7B%5Csqrt%5Bn%5D%7Bb%7D%7D)

Using
:


Answer:
B. $1.60 per notebook
Step-by-step explanation:
Because:
4 notebooks ÷ $2.50 (4 notebooks cost) = $1.60 per notebook
Answer:
Inequality
Step-by-step explanation:
There are an infinite number of quantities less than 6 (5, 4, 3, 2, 1, 0, -1, -2, -3...) so it is much easier to write an inequality