Q. If tanA=34 and cosB=178 and angles A and B are in Quadrant I, find the value of tan(A+B).Answer:
Apply Tangent Addition Formula: Use the tangent addition formula: tan(A+B)=1−tanA⋅tanBtanA+tanB. First, we need to find tanB. Since cosB=178 and B is in Quadrant I, where all trigonometric functions are positive, we can find sinB using the Pythagorean identity sin2B+cos2B=1.
Calculate sin B: Calculate sin B: sin2B=1−cos2B=1−(178)2=1−28964=289289−64=289225. Therefore, sinB=289225=1715, since we are in Quadrant I and sine is positive.
Find tanB: Now, find tanB using the quotient of sinB and cosB: tanB=cosBsinB=1781715=815.
Substitute tan values: Substitute the values of tanA and tanB into the tangent addition formula: tan(A+B)=1−tanA⋅tanBtanA+tanB=1−(34)⋅(815)(34)+(815).
Simplify numerator: Simplify the numerator: (34)+(815)=(2432)+(2445)=(2432+45)=2477. Simplify the denominator: 1−(34)×(815)=1−(2460)=(2424)−(2460)=24−36=2−3.
Simplify denominator: Now, divide the numerator by the denominator: tan(A+B)=2477/(−23)=2477⋅(−32)=−72154.
Divide numerator by denominator: Simplify the fraction−154/72 by dividing both numerator and denominator by their greatest common divisor, which is 2: tan(A+B)=(−154/2)/(72/2)=−77/36.
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