Given that cosA=523 and sinB=621, and that angles A and B are both in Quadrant I, find the exact value of sin(A+B), in simplest radical form.Answer:
Q. Given that cosA=523 and sinB=621, and that angles A and B are both in Quadrant I, find the exact value of sin(A+B), in simplest radical form.Answer:
Use Sine Addition Formula: Use the sine addition formula: sin(A+B)=sin(A)cos(B)+cos(A)sin(B).We need to find sin(A) and cos(B).
Find sin(A) and cos(B): Since A is in Quadrant I, sin(A) is positive. We can find sin(A) using the Pythagorean identity: sin2(A)+cos2(A)=1. We know cos(A)=523, so cos2(A)=2523. sin2(A)=1−cos2(A)=1−2523=2525−2523=252. sin(A)=sin2(A)=252=52.
Find sin(B) and cos(B): Since B is in Quadrant I, cos(B) is also positive. We can find cos(B) using the Pythagorean identity: sin2(B)+cos2(B)=1. We know sin(B)=621, so sin2(B)=3621. cos2(B)=1−sin2(B)=1−3621=3636−3621=3615=125 after simplifying. cos(B)=cos2(B)=125=125=235=2⋅353=615 after rationalizing the denominator.
Plug in Values: Now we have sin(A)=52 and cos(B)=615. Plug these values into the sine addition formula: sin(A+B)=sin(A)cos(B)+cos(A)sin(B). sin(A+B)=(52)(615)+(523)(621).
Simplify Expression: Simplify the expression: sin(A+B)=5⋅62⋅15+5⋅623⋅21.sin(A+B)=3030+30483.
Combine Terms: Combine the terms over a common denominator: sin(A+B)=(30+483)/30. Since 483 can be simplified to 3×161=3×161=3×7×23=3×7×23, we can rewrite the expression. sin(A+B)=(30+3×7×23)/30.
Simplify Further: Simplify the expression further: sin(A+B)=(30+3⋅7⋅23)/30.sin(A+B)=(30+3⋅7⋅23)/30=(30+3⋅7⋅23)/30.sin(A+B)=(30+3⋅7⋅23)/30=(30+483)/30.
Final Expression: Notice that 483 was already simplified in a previous step, so we do not need to simplify it again.The final expression for sin(A+B) is 3030+483.
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