Prove the following:

1/(tanØ - secØ ) + 1/(tanØ + secØ) = -2tanØ

(1 - sinØ)/(1 + sinØ) = sec^2Ø - 2secØtanØ + tan^2Ø

User Icon for Reiny Reiny answered
10 years ago

That's a better job of typing it.

I did the first of these in your previous post..

the 2nd:

LS = (1-sinØ)/(1+ sinØ)
= (1-sinØ)/(1+ sinØ) * (1-sinØ)/(1- sinØ)
= (1 - 2sinØ + sin^2 Ø)/(1 - sin^2 Ø)
= (1 - 2sinØ + sin^2 Ø)/cos^2 Ø
= 1/cos^2 Ø - 2sinØ/cos^2 Ø + sin^2 Ø/cos^2Ø
= sec^2 Ø - 2(sinØ/cosØ)*(1/cosØ) + tan^2 Ø
= sec^2 Ø - 2tanØ secØ + tan^2 Ø
= RS

User Icon for Steve Steve answered
10 years ago

or, if you divide top and bottom by cosØ you have

(secØ-tanØ)/(secØ+tanØ)

now multiply top and bottom by (secØ-tanØ) and you have

(secØ-tanØ)^2 / (sec^2Ø-tan^2Ø)
= sec^2Ø - 2secØtanØ + tan^2Ø

User Icon for McKenna Louise McKenna Louise answered
10 years ago

Thanks to the both of you :)

User Icon for Explain Bot Explain Bot answered
11 months ago

To prove the given equation, we will start by manipulating the left side of the equation and simplifying it to match the right side.

Given equation: 1/(tanØ - secØ) + 1/(tanØ + secØ) = -2tanØ

First, let's find a common denominator for the two fractions on the left side. The common denominator is (tanØ - secØ)(tanØ + secØ).

Rewriting the equation with the common denominator:

[(tanØ + secØ) + (tanØ - secØ)] / [(tanØ - secØ)(tanØ + secØ)] = -2tanØ

Now, simplify the numerator:

[tanØ + secØ + tanØ - secØ] / [(tanØ - secØ)(tanØ + secØ)] = -2tanØ

The secØ and -secØ terms cancel out:

[2tanØ] / [(tanØ - secØ)(tanØ + secØ)] = -2tanØ

Now, simplify the denominator:

[2tanØ] / [tan^2Ø - sec^2Ø] = -2tanØ

Using the Pythagorean identity tan^2Ø + 1 = sec^2Ø, we can rewrite the denominator:

[2tanØ] / [tan^2Ø - (tan^2Ø + 1)] = -2tanØ

Simplify the denominator further:

[2tanØ] / [-1] = -2tanØ

Now, simplify the expression:

-2tanØ = -2tanØ

Therefore, we have proven the given equation.

Now, let's prove the second equation:

Given equation: (1 - sinØ)/(1 + sinØ) = sec^2Ø - 2secØtanØ + tan^2Ø

First, express sinØ in terms of cosØ using the Pythagorean identity sin^2Ø + cos^2Ø = 1:

(1 - sinØ)/(1 + sinØ) = sec^2Ø - 2secØtanØ + tan^2Ø

(1 - √(1 - cos^2Ø))/(1 + √(1 - cos^2Ø)) = sec^2Ø - 2secØtanØ + tan^2Ø

Next, convert secØ and tanØ into cosØ:

(1 - √(1 - cos^2Ø))/(1 + √(1 - cos^2Ø)) = (1/cos^2Ø) - 2(1/cosØ)(√(1 - cos^2Ø)) + (√(1 - cos^2Ø))^2

Simplify the right side:

(1 - √(1 - cos^2Ø))/(1 + √(1 - cos^2Ø)) = (1/cos^2Ø) - 2(1/cosØ)(√(1 - cos^2Ø)) + (1 - cos^2Ø)/(1 - cos^2Ø)

Combine the terms on the right side:

(1 - √(1 - cos^2Ø))/(1 + √(1 - cos^2Ø)) = (1 + cos^2Ø - cos^2Ø)/(cos^2Ø - cos^4Ø)

Cancel out the common terms on both sides:

(1 - √(1 - cos^2Ø))/(1 + √(1 - cos^2Ø)) = 1/(1 - cos^2Ø)

Now, expand the numerator of the left side:

1 - √(1 - cos^2Ø) = 1 - cos^2Ø

Simplify further:

√(1 - cos^2Ø) = cos^2Ø

Square both sides to eliminate the square root:

1 - cos^2Ø = cos^4Ø

Now, simplify the equation:

cos^4Ø + cos^2Ø - 1 = 0

This is a quadratic equation in terms of cos^2Ø. Solve for cos^2Ø using factoring or the quadratic formula.

Once you find the values of cos^2Ø, you can substitute them back into the original equation to check if they satisfy the equation. If they do, you have proven the second equation.