OG详解-OG2 数学2 Q18

Choice C is correct. It’s given that triangle  XYZ  is similar to triangle RST, such that X , Y , and Z correspond to R , S , and T, respectively. Since corresponding angles of similar triangles are congruent, it follows that the measure of ∠Z  is congruent to the measure of ∠T. It’s given that the measure of ∠Z  is  20°. Therefore, the measure of ∠T is 20°.
Choice A is incorrect and may result from a conceptual error. Choice B is incorrect. This is half the measure of ∠Z . Choice D is incorrect. This is twice the measure of ∠Z .