Let
x-------> the length side of the original cube
we have

Divide by
both sides

The system of equations is equal to
--------> equation 
--------> equation 
using a graphing tool
see the attached figure
we know that
the solution of the system of equations is the intersection both graphs
therefore
the solution is

therefore
<u>the answer is</u>

Answer:
x = 15°
Step-by-step explanation:
First Identify the angle of x by subtracting 180° - 120° = 60°
Always remember when you see a straight line the line measures 180°
So the angle of x = 60° but not the value of x so use the given equation to find the value of x
3x + 15 = 60°
3x - 15 = -15°
3x = 45
x = 15°
Step-by-step explanation:
Since the triangles are right angled and are similar,
by Pythagoras theorem,
(10√3)^2 = (5√3)^2 + a^2
a = 15, a > 0
Topic: Pythagoras theorem
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(2x + 10) + (6x + 1) = 180 - 79