Q. If cosA=3712 and sinB=53 and angles A and B are in Quadrant I, find the value of tan(A−B).Answer:
Find sinA: We know that cosA=3712. Since A is in Quadrant I, where both sine and cosine are positive, we can find sinA using the Pythagorean identity sin2A+cos2A=1. First, calculate sin2A: sin2A=1−cos2Asin2A=1−(3712)2sin2A=1−1369144sin2A=13691369−1369144cosA=37120 Now, take the square root to find sinA: cosA=37122cosA=37123
Find cosB: We also know that sinB=53. Since B is in Quadrant I, where both sine and cosine are positive, we can find cosB using the Pythagorean identity sin2B+cos2B=1.First, calculate cos2B:cos2B=1−sin2Bcos2B=1−(53)2cos2B=1−259cos2B=2525−259cos2B=2516Now, take the square root to find cosB:sinB=531sinB=532
Calculate tan(A−B): Now we need to find tan(A−B). We can use the formula for the tangent of the difference of two angles:tan(A−B)=1+tanA⋅tanBtanA−tanBWe already have sinA and cosA, and sinB and cosB, so we can find tanA and tanB:tanA=cosAsinAtanA=12/3735/37tanA=1235tanB=cosBsinBtanB=4/53/5tanB=43
Calculate tan(A−B): Now we need to find tan(A−B). We can use the formula for the tangent of the difference of two angles:tan(A−B)=1+tanA⋅tanBtanA−tanBWe already have sinA and cosA, and sinB and cosB, so we can find tanA and tanB:tanA=cosAsinAtanA=12/3735/37tanA=1235tanB=cosBsinBtanB=4/53/5tanB=43Substitute tanA and tanB into the formula for tan(A−B):tan(A−B)=1+tanA⋅tanBtanA−tanBtan(A−B)=1+(1235)⋅(43)1235−43To subtract the fractions, find a common denominator:tan(A−B)=1+(1235)⋅(43)1235−129tanA=cosAsinA0Now simplify the fractions:tanA=cosAsinA1tanA=cosAsinA2tanA=cosAsinA3Now multiply by the reciprocal of the denominator:tanA=cosAsinA4Simplify the fraction by canceling common factors:tanA=cosAsinA5tanA=cosAsinA6tanA=cosAsinA7Finally, simplify the fraction:tanA=cosAsinA8
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