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Find the cosine function that is represented in the graph.

If 1/√5+1/√5+1=p+q√r , find the values of p, q and r

Sanderson is having trouble with his assignment. his shown work is as follows: − 3 7 7 3 = − 3 7 × 7 3 = − 21 21 = −1 however, his answer does not match the answer that his teacher gives him. complete the description of sanderson's mistake. find the correct answer.