Answer:

Step-by-step explanation:
we know that
In the triangle abc
if 
then

Because, the sum of the interior angles in a triangle must be equal to 180 degrees
therefore
Triangle abc is a right triangle
see the attached figure to better understand the problem
The sine of angle a is equal to divide the opposite side to angle a by the hypotenuse
so

The cosine of angle b is equal to divide the adjacent side to angle b by the hypotenuse
so

therefore

When two angles are complementary, the sine of one angle is equal to the cosine of the other angle and the cosine of one angle is equal to the sine of the other angle
so


Subtract 5 from both sides
a/-8 = 4/7 - 5
simplify 4/7 - 5 to 31/-7
a/-8 = 31/-7
multiply both sides by 8
-a = 31/-7 x 8
simplify 31/7 x 8 to 248/7
-a = 248/7
multiply both sides by -1.
The answer is a = 248/7
The words are the explanations of the steps and the dark bolded words are the work shown for each step.
Answer:
Step-by-step explanation:
I answered another one of your questions so I will not explain as much. ther are 12 inches in a foot and then 5280 feet in a mile so that's 1 ft/ 12 in and 1 mi/ 5280 ft. So the math is 20 in * 1 ft/ 12 in * 1 mi/ 5280 ft = .000315 mi.
In reference to the last one, do keep in mind "square" inches and whatnot mean you square things. so 1 ft/ 12 in becomes 1 ft^2/ 144 in^2. Just as a small heads up to what could be tricky.
Your answer would be 66^3 meaning 66 to the power of 3