Prove that :(cosX+Cosy)^2 + (Sinx-Siny)^2 =4Cos^2(x+y/2)

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Select the lengths in centimeters that would form a right triangle

It took alice 5 5/6 hours to drive to her grandparents' house for . on the way home, she ran into traffic and it took her 7 3/8 hours. how much longer did the return trip take? write your answer as a proper fraction or mixed number in simplest form. the trip home took __hours longer. ?