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100 Points! Algebra question. Photo attached. Verify the equation is an identity. Please show as much work as possible. Thank you!

100 Points! Algebra question. Photo attached. Verify the equation is an identity. Please-example-1
User Sanderbee
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1 Answer

3 votes

(sin^2 θ)(csc^2 θ + sec^2 θ) = sec^2 θ


Let's simplify the left side of the equation:

(sin²θ)(csc²θ + sec²θ)

To simplify this expression, we can use the trigonometric identities:

csc² θ = 1/sin² θ

sec² θ = 1/cos² θ

Substituting these identities into the expression, we have:

(sin² θ)(1/sin^2 θ + 1/cos² θ)

Next, we can find a common denominator by multiplying the fractions:

[(sin² θ * cos² θ) + (sin² θ * sin² θ)] / (sin² θ * cos² θ)

Using the identity sin² θ + cos² θ = 1, we can simplify further:

[(sin² θ * cos²θ) + (1 - cos²θ)] / (sin² θ * cos² θ)

Expanding the numerator:

[sin² θ * cos² θ + 1 - cos² θ] / (sin² θ * cos² θ)

Combining like terms:

[sin² θ * cos² θ - cos² θ + 1] / (sin² θ * cos² θ)

Factoring out cos² θ:

[cos² θ (sin² θ - 1) + 1] / (sin² θ * cos² θ)

Using the identity sin² θ - 1 = -cos² θ:

[cos² θ (-cos² θ) + 1] / (sin² θ * cos² θ)

Simplifying the numerator:

[-cos^4 θ + 1] / (sin² θ * cos² θ)

Applying the identity cos² θ = 1 - sin² θ:

[-(1 - sin^² θ)² + 1] / (sin² θ * (1 - sin² θ))

Expanding and simplifying the numerator:

[-(1 - 2sin² θ + sin² θ) + 1] / (sin² θ * (1 - sin² θ))

Distributing the negative sign:

[-1 + 2sin² θ - sin^4 θ + 1] / (sin² θ * (1 - sin² θ))

Canceling out the -1 and +1 terms:

[2sin² θ - sin^4 θ] / (sin² θ * (1 - sin² θ))

Using the identity 1 - sin² θ = cos² θ:

[2sin² θ - sin^4 θ] / (sin² θ * cos² θ)

Rearranging the terms:

[(sin² θ)(2 - sin² θ)] / (sin² θ * cos² θ)

Canceling out the sin² θ terms:

(2 - sin² θ) / cos² θ

Using the identity 2 - sin² θ = 1 + cos² θ:

(1 + cos² θ) / cos² θ

Simplifying further:

1/cos^

2 θ + cos² θ/cos² θ

Which equals:

sec² θ + 1

Therefore, the left side of the equation simplifies to sec^2 θ + 1, not just sec² θ.

User Meesinlid
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