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Grade 11Trigonometry

sin(x+y)/sin(x-y)=a+b/a-b then tanx/tany=?
a.b/a
b.a/b

Profile image of SanchiSSonawane
7 Years agoGrade 11
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1 Answer

Profile image of Anish Singhal
ApprovedApproved Tutor Answer7 Years ago

To tackle the equation you've presented, we need to delve into some trigonometric identities and algebraic manipulations. The equation given is:

sin(x+y)/sin(x-y) = (a+b)/(a-b).

Our goal is to find out what tan(x) divided by tan(y) equals in terms of a and b. Let's break it down step by step.

Using the Sine Addition and Subtraction Formulas

We can start by applying the sine addition and subtraction formulas:

  • sin(x+y) = sin(x)cos(y) + cos(x)sin(y)
  • sin(x-y) = sin(x)cos(y) - cos(x)sin(y)

This allows us to rewrite the left side of the equation:

sin(x+y)/sin(x-y) = (sin(x)cos(y) + cos(x)sin(y)) / (sin(x)cos(y) - cos(x)sin(y)).

Setting Up the Equation

Now, we can set this equal to the right side of your equation:

(sin(x)cos(y) + cos(x)sin(y)) / (sin(x)cos(y) - cos(x)sin(y)) = (a+b)/(a-b).

Cross-Multiplying

Next, we can cross-multiply to eliminate the fraction:

(sin(x)cos(y) + cos(x)sin(y))(a-b) = (a+b)(sin(x)cos(y) - cos(x)sin(y)).

Distributing Terms

By distributing both sides, we can simplify the equation to:

a sin(x)cos(y) - b sin(x)cos(y) + a cos(x)sin(y) - b cos(x)sin(y) = a sin(x)cos(y) + b sin(x)cos(y) - a cos(x)sin(y) - b cos(x)sin(y).

Rearranging and Isolating Terms

Rearranging the terms will help us isolate the variables involving tan(x) and tan(y). This gives us:

2a sin(x)cos(y) - 2b cos(x)sin(y) = 0.

Dividing by Common Terms

We can then factor out common terms, leading us to:

2a sin(x)cos(y) = 2b cos(x)sin(y).

Finding the Ratio of Tangents

Now, dividing both sides by cos(x)cos(y) gives us:

(a/b) = (sin(y)/cos(y)) / (sin(x)/cos(x)),

which simplifies to:

a/b = tan(y)/tan(x).

Final Expression

Rearranging this yields:

tan(x)/tan(y) = b/a.

So, in conclusion, the relationship between tan(x) and tan(y) is expressed as:

tan(x)/tan(y) = b/a.

This means that if you know the values of a and b, you can easily determine the ratio of the tangents of the angles x and y. This result shows how intertwined trigonometric functions are with algebraic expressions. It's a beautiful interplay of different branches of mathematics!