In triangle ABC, let a /sinA + b/sinB + c/sinC = k, where A,B and C are interior angles.
a) Show that a / sinA = a+b+c / sinA+sinB+sinC
b) Show that sinA+sinB+sinC = 4cosA/2 cosB/2 cosC/2
收錄日期: 2021-04-24 09:16:22
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