In △PQR it is given that PQ=PR. A point S is chosen on PQ such that PS=PR, and a point T is chosen on PR such that PT=PQ. Answer the following.
a. (i) Write the two equalities that are directly provided by the construction.
b. (ii) Prove that PS=PT.
c. (iii) What kind of triangle is △PST with respect to its sides? Give a brief reason for your answer.