Answer:
b = 33 miles
Step-by-step explanation:
The illustration forms a right angled triangle. The opposite side of the triangle is where we are looking for . The adjacent side is the radius 4000 miles.
5280 ft = 1 mile
735 ft = ? miles
cross multiply
735/5280
miles = 0.13920454545 miles
The hypotenuse side is the height of the building + 4000 miles = 0.140 + 4000 = 4000.14 miles
using Pythagoras theorem
c² = a² + b²
c = 4000.14
a = 4000
4000.14² = 4000² + b²
b² = 4000.14² - 4000²
b² = 16001120.0196 - 16000000
b² = 1120.0196
b = √1120.0196
b = 33.4666938911
b = 33 miles
The answer to this would be 5x+6>=21. Just wanted points :P
The first is a. you can rewrite it

the second is d. the only common factor between 20 and 40 that can be taken out is the 4 which becomes a 2, but inside the square roots there is still a 5 and 10, which cannot be combined
the third is c.

the fourth is d.
add 3 to both sides

then square both sides

then divide both sides by 2, x=50