Problem
QUESTION 4 The two triangles below are similar. Find the missing length(s). \( x=21 \) \( x=7 \) \( x=28 \) \( x=12 \)
Solution
Step 1 ：\( x_1 = \frac{x_2}{x_3} \times x_4 \)
Step 2 ：\( x_1 = \frac{7}{28} \times 12 \)
Step 3 ：\( x_1 = \frac{12}{4} \)
