Triangle 1 and Triangle 2, shown below, are similar triangles.

triangle 1 angles 4, 6, and x
triangle 2 angles 6, 9, and 10.5
Which proportion can be used to find side x on Triangle 1?
A. 6/9 = x/6
B. 6/4 = 10.5/x
C. 4/6 = 10.5/x
D. 9/4 = x/6

A. 6/9 = x/6

This proportion represents the ratio of corresponding sides in similar triangles. By cross multiplying, we can solve for x:

6 * x = 9 * 6
6x = 54
x = 9

Therefore, the value of side x in Triangle 1 is 9.