Apply Trigonometric Identity: Let's use the identity sin(c)sin(d)=21[cos(c−d)−cos(c+d)] to simplify the integral.So, sin(x−a)sin(x−b)=21[cos((x−a)−(x−b))−cos((x−a)+(x−b))].
Simplify the Integral: This simplifies to 21[cos(b−a)−cos(2x−a−b)]. Now, I=∫21[cos(b−a)−cos(2x−a−b)]dx.
Factor Out Constants: We can take out the constant term 21 and cos(b−a) from the denominator, so I=cos(b−a)−cos(2x−a−b)2∫dx.
Use Substitution: Now, let's use the substitution u=2x−a−b, which means du=2dx. So, dx=2du.
Integrate with Substitution: Substitute back into the integral, we get I=2∫(2du)/[cos(b−a)−cos(u)]. This simplifies to I=∫(cos(b−a)−cos(u)du).
Split Integral: Now, we can split the integral into two parts: I=∫cos(b−a)du−∫cos(u)du.
Evaluate First Integral: The first integral ∫cos(b−a)du is just cos(b−a)u since cos(b−a) is a constant.
Evaluate Second Integral: The second integral ∫cos(u)du is a standard integral that equals ln∣sec(u)+tan(u)∣.
Combine Results: So, I=cos(b−a)u−ln∣sec(u)+tan(u)∣+C, where C is the constant of integration.
Substitute Back and Simplify: Now, substitute back u=2x−a−b to get I in terms of x. I=cos(b−a)2x−a−b−ln∣sec(2x−a−b)+tan(2x−a−b)∣+C.
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