Q. If cosA=2921 and tanB=125 and angles A and B are in Quadrant I, find the value of tan(A+B).Answer:
Find tanA: Use the identity for the tangent of the sum of two angles: tan(A+B)=1−tanA⋅tanBtanA+tanB. First, we need to find tanA. Since we know cosA=2921 and A is in Quadrant I, we can find sinA using the Pythagorean identity sin2A+cos2A=1. sin2A=1−cos2Asin2A=1−(2921)2sin2A=1−841441tan(A+B)=1−tanA⋅tanBtanA+tanB0tan(A+B)=1−tanA⋅tanBtanA+tanB1tan(A+B)=1−tanA⋅tanBtanA+tanB2tan(A+B)=1−tanA⋅tanBtanA+tanB3 Now, tan(A+B)=1−tanA⋅tanBtanA+tanB4tan(A+B)=1−tanA⋅tanBtanA+tanB5tan(A+B)=1−tanA⋅tanBtanA+tanB6
Substitute values into identity: Now we have tanA=2120 and tanB=125. We can substitute these values into the identity for tan(A+B). tan(A+B)=(1−tanA⋅tanB)(tanA+tanB)tan(A+B)=(1−(2120⋅125))(2120+125)
Simplify numerator and denominator: Simplify the numerator and the denominator separately.For the numerator:tanA+tanB=2120+125To add these fractions, find a common denominator, which is 21×12=252.(2120)×(1212)+(125)×(2121)=252240+252105=252240+105=252345For the denominator:1−(2120×125)=1−252100To subtract these fractions, express 1 as 252252.(252252)−252100=252252−100=252152
Divide to find tan(A+B): Now we can divide the numerator by the denominator to find tan(A+B).tan(A+B)=252345/252152When dividing by a fraction, multiply by the reciprocal of the divisor.tan(A+B)=252345×152252The 252 in the numerator and denominator cancel out.tan(A+B)=152345
Simplify final fraction: Simplify the fraction 152345 if possible.345 and 152 have no common factors other than 1, so the fraction is already in its simplest form.
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