If you divide a number by 9 then that number is repeated (1/9 = 0.111111... or 2/9 = 0.22222....)
So if we want 94 to repeat in the decimal 0.194 then we can have 94/99. But the thing is that we don't have 94 being repeated starting from the tenths place so we can possibly do 94/990.
Now we do have a tenths with a zero but we need a one to replace that zero. To do that we have to add 1/10 + 94/990 = 99/990 + 94/990 = 193/990.
In a parallelogram, opposite angles are congruent.
This means that the four angles of the parallelogram are:

Moreover, the sum of the interior angles of a polygon with n sides is 180(n-2). So, the sum of the interior angles of a parallelogram is 360.
This means

And since
, we have 
Let
and
. Then


and


The expression under the square root can be rewritten as

Recall that

so that

and assuming
and
, we end up with

so that

as required.
[ 1 ] Given
[ 2 ] Exterior Sides Opposite Rays
[ 3 ] Definition of Supplementary angles
[ 4 ] First substitution
[ 5 ] Subtraction Property of Equality
[ 6 ] Second Substitution
[ 7 ] If corrsp. equal, the lines ||
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