Q. Let x and y be functions of t with y=15cosx. If dtdx=−91, what is dtdy when x=6π?Write an exact, simplified answer.
Differentiation using chain rule: Step 1: Use the chain rule for differentiation to find dtdy. Given y=15cos(x), differentiate both sides with respect to t. dtdy=15⋅(−sin(x))⋅dtdx
Substitute given values: Step 2: Substitute the given values into the differentiated equation.dtdx=−91 and x=6πdtdy=15⋅−sin(6π)⋅(−91)
Calculate and simplify: Step 3: Calculate sin(6π) and simplify the expression.sin(6π)=21dtdy=15×−21×(−91)dtdy=15×21×91dtdy=1815dtdy=65
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