Q. If cosA=419 and tanB=125 and angles A and B are in Quadrant I, find the value of tan(A−B).Answer:
Use tan(A−B) Identity: Use the identity for tan(A−B), which is tan(A−B)=1+tanA⋅tanBtanA−tanB. We need to find tanA and tanB to use this formula.
Find sinA: We know that cosA=419 and tanB=125. Since A is in Quadrant I, sinA will be positive. Use the Pythagorean identity sin2A+cos2A=1 to find sinA.sin2A=1−cos2Asin2A=1−(419)2sin2A=1−168181cosA=4190cosA=4191cosA=4192cosA=4193
Find tanA: Now, find tanA using the definition tanA=cosAsinA.tanA=(9/41)(40/41)tanA=940
Substitute tanA and tanB: Substitute the values of tanA and tanB into the identity for tan(A−B).tan(A−B)=1+tanA⋅tanBtanA−tanBtan(A−B)=1+(940)⋅(125)940−125
Simplify with Common Denominator: Simplify the expression by finding a common denominator for tanA and tanB.tan(A−B)=(940×1212−125×99)/(1+940×125)tan(A−B)=(108480−10845)/(1+108200)tan(A−B)=(108435)/(1+108200)
Simplify Denominator: Simplify the denominator of the expression. 1+108200=108108+1082001+108200=108308
Divide Numerator by Denominator: Now, divide the numerator by the denominator.tan(A−B)=108435/108308tan(A−B)=108435×308108
Simplify Expression: Simplify the expression by canceling out the common factor of 108. tan(A−B)=308435
Check for Further Simplification: Check if the fraction can be simplified further. 435 and 308 have no common factors other than 1, so the fraction is already in its simplest form.
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