CPhill

secA   =  r /x

r = √ [ x^2 + y^2]  = √ [ (7^2) + (–4^2) ]  = √ 65

So

sec A  =  √ 65 / 7

Les Miserables  is about 1500 pages...[more or less]...!!!!

The first  and last ones may be a little "advanced" for you, MJ

The second  wouldn't.....you can read the unabridged version here :

http://www.gutenberg.org/files/135/135-h/135-h.htm

Caution.....it is L O N G  !!!!!!!......maybe a better Summer reading book.....also....the abridged version is probably just as good....but....you  will have to seek that  out......!!!!!

9 / [ √3 / 2]   =

[9 /1] * [ 2 / √3 ]  =

18/ √3      multiply top/bottom by  √3

18 * √3  / [ √3 *√3]  =

[18 * √3 ]  / 3  =

18/3   * √3   =

6 √3

"Grapes of Wrath'  by John Steinbeck 

"Les Miserables"  by  Victor Hugo

"Moby D**k" by Herman Melville

The second Guest's answer is correct....

Here you go :   http://www.purplemaths.com/modules/distform.htm

12 x 1086     will give you the answer

C  = 2 * pi * radius   =  2 * pi *  24   =   48 pi   ≈   150.8

12000=0.01328*20^2*V^3       solve for V

Divide both sides by   0.01328*20^2

12000 / ( 0.01328 * 20^2)  =  V^3       take the cube root of both sides

[12000 / ( 0.01328 * 20^2)]^(1/3)  =  V  ≈  13.12