In the figure, use similar triangles and the fact that corresponding sides are proportional to find the missing length.

The missing length, x, is equal to 7 m.

Explanation:

In the figure, the two triangles are similar because they show two pairs of congruent angles and one pair of different sides.

The two upper vertices are marked each with a line which indicates that they are congruent, i.e. they have the same measure.Also, the small squares shown in each of the bases indicate that those two angles are right, i.e. they measure 90°.Since the two sides adjacent to the right angles have different lengths, the triangles are not congruent but similar.

By similarity, you can state that the corresponding parts keep the same ratio. Thus:

x / 8m = 21m / 24mx = 8m × 21 m / 24 m (muliply both sides by 8m)x = 21 m / 3 (simplify dividing numerator and denominator by 8m)x = 7 m (simplify dividing by 3)

         Answer x = 7 m