Q. Let g(x)=sin(x)cos(x).Find g′(x).Choose 1 answer:(A) −sin2(x)1(B) sin2(x)sin2(x)−cos2(x)(C) sin2(x)1(D) sin2(x)cos2(x)−sin2(x)
Recognize Function Type: Recognize that g(x)=sin(x)cos(x) is a quotient of two functions, where the numerator is cos(x) and the denominator is sin(x). To find the derivative g′(x), we will use the quotient rule.
Apply Quotient Rule: The quotient rule states that if we have a function h(x)=g(x)f(x), then its derivative h′(x) is given by h′(x)=(g(x))2f′(x)g(x)−f(x)g′(x). Here, f(x)=cos(x) and g(x)=sin(x).
Find Derivative of Cos(x): Find the derivative of the numerator f(x)=cos(x). The derivative of cos(x) with respect to x is −sin(x).
Find Derivative of Sin(x): Find the derivative of the denominator g(x)=sin(x). The derivative of sin(x) with respect to x is cos(x).
Apply Quotient Rule: Apply the quotient rule using the derivatives from steps 3 and 4. So, g′(x)=(sin(x))2−sin(x)⋅sin(x)−cos(x)⋅cos(x).
Simplify Expression: Simplify the expression for g′(x). We have g′(x)=sin2(x)−sin2(x)−cos2(x).
Apply Pythagorean Identity: Recognize that sin2(x)+cos2(x)=1, which is the Pythagorean identity. Therefore, −sin2(x)−cos2(x)=−1.
Substitute Identity: Substitute the Pythagorean identity into the expression for g′(x) to get g′(x)=−sin2(x)1.
Final Simplified Form: The final simplified form of g′(x) is g′(x)=−sin2(x)1, which corresponds to answer choice (A).
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