ElectricPavlov

Angle o is 60 degrees (equilateral triangle)

60 / 360    x    pi  x 8^2 -   8^2 sqrt3/4                 red is area of equilateral triangle  

Yikes....   the second digit can only go as high as 5 ....

Here is my answer:

of course they are!

(2x + 3x) - 1 = 0

5x -1 = 0

the 12 - 16 triangle has a hypotenuse of 20  (via pythag theorem)

20 is to 16      as     x  is to 20

20/16 = x/20

x = 25

In a right triangle.....one angle is 90^o      the other two add to 90^o

   in ratio of 3 to 7     one is   3 /(3+7) = 3/10^ths   of 90      3/10 x 90 = 27^o

                          and the other is   7/(3+7) = 7/10^ths   of 90 =               63^o

2 the angles add to 90

     x = one     the other is    2x -30

x    +    2x-30   = 90

 x =40          one angle is 40^o    the other   is    2x-30   =   50^o

12 liters final

x = 10%

12-x = 100% solution

.1 x   +   1 (12-x)   ==  .3 (12)

.1x + 12 - x = 3.6

.9x =8.4

x = 9 1/3   liters of 10%

This is just a tedious exercise:

-4 + 9i     +   6 - 6i  ==  11-12i   +  (-9+15i)  

2 + 3i                     ==  2 + 3i

from 1000 to 9999  is   9000 numbers

   stating with 1001  and ending with 9996    there are   9000/7 =~ 1286 numbers  ARE divisible by 7....

          you can finish.....

Alright, Knucklehead 

the diagonal is 2 * height of the equilateral triangles       using side length = L

  height :

      sin 60 = height/L

        L sin 60 = height                   sin 60    is   sqrt 3/2

            2 * height then equals   L sqrt 3   = AD 

then   AD      to      BC  which equals L   becomes      Lsqrt3  / L    = sqrt 3