Step-by-step explanation:




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
:


Step 2: She did not simplify under the square root correctly
under the square root:
(-6)^2 =36
and -4(5)(-8) =160
therefore under the square root it needs to be square root of 36+160 which is square root of 196.
That answer is 14 when square rooted
There is exactly 8333.3333 feet in one million inches
Answer:
See attachment below
Step-by-step explanation: