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27 choose the appropriate value for x for the following similar triangl…

Question

27 choose the appropriate value for x for the following similar triangles given below. △abc ~ △xyz. (image of two right triangles: △abc with right angle at c, bc=40, ab=50; △xyz with right angle at z, yz=20, hypotenuse xy=x. options: a) 25, b) 30, c) 60, d) 100)

Explanation:

Step1: Identify corresponding sides

In similar triangles \( \triangle ABC \sim \triangle XYZ \), the hypotenuse of \( \triangle ABC \) is \( AB = 50 \), the base \( BC = 40 \). For \( \triangle XYZ \), the base \( YZ = 20 \), and hypotenuse \( XY = x \). The ratio of corresponding sides should be equal. So, \( \frac{BC}{YZ}=\frac{AB}{XY} \).

Step2: Substitute values

Substitute \( BC = 40 \), \( YZ = 20 \), \( AB = 50 \), and \( XY = x \) into the proportion: \( \frac{40}{20}=\frac{50}{x} \).

Step3: Solve for \( x \)

Simplify \( \frac{40}{20}=2 \), so the equation becomes \( 2=\frac{50}{x} \). Cross - multiply: \( 2x = 50 \), then \( x=\frac{50}{2}=25 \). Wait, no, wait. Wait, maybe I mixed up the corresponding sides. Let's re - check. \( \triangle ABC \) has right angle at \( C \), \( \triangle XYZ \) has right angle at \( Z \). So, \( BC \) corresponds to \( YZ \), and \( AB \) corresponds to \( XY \)? Wait, no, maybe \( BC \) (length 40) corresponds to \( YZ \) (length 20), and \( AB \) (length 50) corresponds to \( XY \) (length \( x \))? Wait, no, the ratio of \( BC \) to \( YZ \) is \( 40/20 = 2 \), so the ratio of \( AB \) to \( XY \) should also be 2? Wait, no, that gives \( 50/x = 2 \), \( x = 25 \), but let's check again. Wait, maybe \( AC \) is the other leg. Let's find \( AC \) first. In \( \triangle ABC \), using Pythagoras: \( AC=\sqrt{AB^{2}-BC^{2}}=\sqrt{50^{2}-40^{2}}=\sqrt{2500 - 1600}=\sqrt{900}=30 \). Oh! I made a mistake earlier. The right angle is at \( C \), so \( AC \) and \( BC \) are legs, \( AB \) is hypotenuse. In \( \triangle XYZ \), right angle at \( Z \), so \( XZ \) and \( YZ \) are legs, \( XY \) is hypotenuse. So, \( BC = 40 \) (leg of \( \triangle ABC \)), \( YZ = 20 \) (leg of \( \triangle XYZ \)), \( AC = 30 \) (leg of \( \triangle ABC \)), \( XZ \) (leg of \( \triangle XYZ \)), and \( AB = 50 \) (hypotenuse of \( \triangle ABC \)), \( XY = x \) (hypotenuse of \( \triangle XYZ \)). So the ratio of legs: \( \frac{BC}{YZ}=\frac{40}{20}=2 \), so the ratio of hypotenuses should be the same. Wait, no, the ratio of \( AC \) (30) to \( XZ \) should also be 2, and \( AB \) (50) to \( XY \) (x) should be 2? Wait, no, \( \frac{BC}{YZ}=\frac{40}{20}=2 \), so \( \frac{AB}{XY}=\frac{50}{x}=2 \)? No, that's not right. Wait, \( AC = 30 \), \( YZ = 20 \), \( BC = 40 \), \( XZ \) is the other leg. Wait, maybe \( BC \) (40) corresponds to \( XZ \), and \( AC \) (30) corresponds to \( YZ \) (20)? Let's check the ratio of \( AC \) to \( YZ \): \( 30/20 = 1.5 \), and \( BC \) to \( XZ \): \( 40/XZ = 1.5 \), then \( XZ=\frac{40}{1.5}=\frac{80}{3}\), which is not helpful. Wait, no, let's start over. Since \( \triangle ABC \sim \triangle XYZ \), the order of the letters matters. So \( A \) corresponds to \( X \), \( B \) corresponds to \( Y \), \( C \) corresponds to \( Z \). So, \( AB \) corresponds to \( XY \), \( BC \) corresponds to \( YZ \), \( AC \) corresponds to \( XZ \). So \( BC = 40 \), \( YZ = 20 \), so the scale factor is \( \frac{BC}{YZ}=\frac{40}{20}=2 \). Therefore, \( AB \) (length 50) corresponds to \( XY \) (length \( x \)), so \( \frac{AB}{XY}=2 \), so \( \frac{50}{x}=2 \), \( x = 25 \)? But wait, when we calculated \( AC=\sqrt{50^{2}-40^{2}} = 30 \). Then, if \( AC \) corresponds to \( XZ \), and \( YZ = 20 \), \( BC = 40 \), then the ratio of \( BC \) to \( YZ \) is 2, so \( AC \) (30) should correspond to \( XZ \), and \( XZ=\frac{30}{2}=15 \), and \( XY \) (hypotenuse of \( \triangle XYZ \)) should be \( \sqrt{15^{2}+20^{2}}=\sqrt{225 + 400}=\sqrt{625}=25 \). Ah, there we go. So \( x = 2…

Answer:

A. 25