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If 
cos A=(4)/(5) and 
tan B=(11)/(60) and angles A and B are in Quadrant I, find the value of 
tan(A+B).
Answer:

If cosA=45 \cos A=\frac{4}{5} and tanB=1160 \tan B=\frac{11}{60} and angles A and B are in Quadrant I, find the value of tan(A+B) \tan (A+B) .\newlineAnswer:

Full solution

Q. If cosA=45 \cos A=\frac{4}{5} and tanB=1160 \tan B=\frac{11}{60} and angles A and B are in Quadrant I, find the value of tan(A+B) \tan (A+B) .\newlineAnswer:
  1. Find sinA\sin A: We know that cosA=45\cos A = \frac{4}{5}. To find tanA\tan A, we need to find sinA\sin A using the Pythagorean identity sin2A+cos2A=1\sin^2 A + \cos^2 A = 1.\newlineSubstitute cosA=45\cos A = \frac{4}{5} into the identity:\newline(\sin A)^\(2 + \left(\frac{44}{55}\right)^22 = 11
  2. Simplify equation: Simplify the equation to find (sinA)2(\sin A)^2:(sinA)2+1625=1(\sin A)^2 + \frac{16}{25} = 1(sinA)2=11625(\sin A)^2 = 1 - \frac{16}{25}(sinA)2=25251625(\sin A)^2 = \frac{25}{25} - \frac{16}{25}(sinA)2=925(\sin A)^2 = \frac{9}{25}
  3. Take square root: Take the square root of both sides to find sinA\sin A:sinA=±925\sin A = \pm\sqrt{\frac{9}{25}}Since angle A is in Quadrant I, where sine is positive, we choose the positive root:sinA=35\sin A = \frac{3}{5}
  4. Find tanA\tan A: Now we can find tanA\tan A using sinA\sin A and cosA\cos A:
    tanA=sinAcosA\tan A = \frac{\sin A}{\cos A}
    tanA=3/54/5\tan A = \frac{3/5}{4/5}
    tanA=34\tan A = \frac{3}{4}
  5. Use angle sum identity: We are given tanB=1160\tan B = \frac{11}{60}. To find tan(A+B)\tan(A+B), we use the angle sum identity for tangent:\newlinetan(A+B)=tanA+tanB1tanAtanB\tan(A+B) = \frac{\tan A + \tan B}{1 - \tan A \cdot \tan B}\newlineSubstitute tanA=34\tan A = \frac{3}{4} and tanB=1160\tan B = \frac{11}{60} into the identity:\newlinetan(A+B)=34+11601(34)(1160)\tan(A+B) = \frac{\frac{3}{4} + \frac{11}{60}}{1 - \left(\frac{3}{4}\right) \cdot \left(\frac{11}{60}\right)}
  6. Find common denominator: Find a common denominator and simplify the numerator and denominator:\newlinetan(A+B)=45/60+11/60133/240\tan(A+B) = \frac{45/60 + 11/60}{1 - 33/240}\newlinetan(A+B)=56/60133/240\tan(A+B) = \frac{56/60}{1 - 33/240}\newlinetan(A+B)=56/60(240/240)(33/240)\tan(A+B) = \frac{56/60}{(240/240) - (33/240)}\newlinetan(A+B)=56/60207/240\tan(A+B) = \frac{56/60}{207/240}
  7. Simplify fractions: Simplify the fractions and perform the division:\newlinetan(A+B)=1415/207240\tan(A+B) = \frac{14}{15} / \frac{207}{240}\newlinetan(A+B)=1415×240207\tan(A+B) = \frac{14}{15} \times \frac{240}{207}\newlinetan(A+B)=14×24015×207\tan(A+B) = \frac{14 \times 240}{15 \times 207}
  8. Perform division: Simplify the multiplication and division: tan(A+B)=33603105\tan(A+B) = \frac{3360}{3105} Now we simplify the fraction by dividing both the numerator and the denominator by their greatest common divisor, which is 1515: tan(A+B)=224207\tan(A+B) = \frac{224}{207}

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