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12. Trigonometric Identities
12. Trigonometric Identities / Sum and Difference Identities / Problem 6
Problem 6

Find the exact value of cos(x−y)\(\cos\)\(\left\)(x-y\(\right\)) . Use a trigonometric identity.
cosx=511\(\cos\) x=\(\frac{5}{11}\), siny=−18\(\sin\) y=-\(\frac\)18, xx in fourth quadrant, yy in third quadrant