Q. If tanA=1235 and cosB=2921 and angles A and B are in Quadrant I, find the value of tan(A+B).Answer:
Use tan(A+B) Formula: Use the formula for tan(A+B), which is tan(A+B)=1−tanA⋅tanBtanA+tanB. We know tanA=1235, but we need to find tanB using the given cosB=2921.
Find tanB: To find tanB, we first need to find sinB. Since cos2B+sin2B=1, we can solve for sinB. sin2B=1−cos2Bsin2B=1−(2921)2sin2B=1−(841441)sin2B=(841−441)/841sin2B=841400tanB0tanB1, since tanB2 is in Quadrant I, sinB is positive.
Calculate tanB: Now that we have sinB, we can find tanB. tanB=cosBsinB tanB=21/2920/29 tanB=2120
Substitute tanA and tanB: Substitute tanA and tanB into the tan(A+B) formula.tan(A+B)=1−tanA⋅tanBtanA+tanBtan(A+B)=1−(1235⋅2120)1235+2120
Simplify numerator and denominator: Simplify the numerator and the denominator separately.First, find a common denominator for the numerator.The common denominator for 12 and 21 is 84.tan(A+B)=(12×735×7+21×420×4)/(1−1235×2120)tan(A+B)=84245+8480/(1−252700)
Continue simplifying: Continue simplifying the numerator and the denominator.tan(A+B)=84325/(1−252700)Now, simplify the denominator:1−252700=252252−2527001−252700=252252−7001−252700=252−4481−252700=63−56 (simplifying the fraction by dividing both numerator and denominator by 4)
Divide numerator by denominator: Now, divide the numerator by the denominator.tan(A+B)=84325/63−56To divide by a fraction, multiply by its reciprocal.tan(A+B)=84325×−5663
Simplify multiplication: Simplify the multiplication.tan(A+B)=84×−56325×63tan(A+B)=−470420475tan(A+B)=−470420475 (keeping the negative sign in the numerator)
Check for further simplification: Check if the fraction can be simplified further.Both 20475 and 4704 are divisible by 3.tan(A+B)=1568−6825This fraction cannot be simplified further.
More problems from Find trigonometric ratios using multiple identities