It looks familiar, but I'm not quite sure which triangle formula this is. All credit goes to ChrisAWJB (he wanted me to post this for him).
EDIT: It calculates the area of a triangle, and it is called Heron's Formula. (Thanks to that from Xeda and Timothy.)
:a+bi ;This is located under MODE :Prompt A,B,C :.5(A+B+C :Pause √(Ans(Ans-A)(Ans-B)(Ans-C :DelVar ADelVar BDelVar C
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