Answer:
9. ∠A ≅ ∠R
10. SI ≅ GH
11. MN ≅ RN
12. FE ≅ TU
Explanation:
Look at the reason identifier: A means "angle"; S means "side". The order is important. AAS means two adjacent angles with only one of them next to the corresponding sides. SAS means the angle is between two corresponding sides.
9. Sides CS and TS correspond and are congruent. The vertical angles at S are congruent, so the AAS identifier means you're looking for angles A and R to be congruent. (Using angles C and T would invoke the ASA identifier.)
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10. Sides HI are congruent; the angles at H and I are congruent. The SAS identifier means you're looking for the sides on the other side of those angles to be congruent: sides SI and GH.
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11. SSS means you're claiming all three sides are congruent to their corresponding sides. The common side is congruent to itself; the marked sides are congruent. So, you need the unmarked sides to be congruent to each other.
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12. HL means you're claiming the hypotenuse and one leg of the right triangle are congruent. One leg is already marked, so you need the hypotenuses to be congruent.