Answer:
6
Step-by-step explanation:
Find the ratio between the two triangles:
x is parallel to side 9
10 is parallel to an unknown quantity (Which is 15 if you need that later)
8 is parallel to side 12
Considering we only have known quantities with 8 and 12, we will use those.
12÷8 = 1.5
Therefore, the ratio between the two triangles is 1.5
Since we know the bigger length of the triangle, we will divide to get an obviously smaller quantity.
9÷1.5 = x
x=6
or,
You can find the hypotenuse (even though that's obviously not what the lesson is but why not?).
a²+b² = c² is the formula.
x²+8² = 10²
x²+ 64 = 100
x² = 36
√36 = 6
So, x is equal to 6.
Hope this helps!
