If [theta] is an acute angle with sin[theta]=3/5, find the exact value of cos2[theta]. This is the last one I am stumped on.
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Originally Posted by gretchen If [theta] is an acute angle with sin[theta]=3/5, find the exact value of cos2[theta]. This is the last one I am stumped on. Call theta = t for simplicity. cos^2(t) = 1 - 2*sin^2(t) = 1 - 2*(3/5)^2 = 1 - 2*9/25 = 1 - 18/25 = 7/25 -Dan
You may use the formula to solve the questions related to this as cos 2(theta)=cos^2 (theta) - sin^2 (theta) = 1- 2*sin^2 (theta) = 2*cos^2 (theta) - 1 These are the formulas to solve the problem
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