The trigonometric identity (cos⁴θ - sin⁴θ)/(1 - tan⁴θ) = cos⁴θ
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How to solve the trigonometric identity?</h3>
Since (cos⁴θ - sin⁴θ)/(1 - tan⁴θ) = [(cos²θ)² - (sin²θ)²]/[1 - (tan²θ)²]
Using the identity a² - b² = (a + b)(a - b), we have
(cos⁴θ - sin⁴θ)/(1 - tan⁴θ) = [(cos²θ)² - (sin²θ)²]/[1 - (tan²θ)²]
= (cos²θ - sin²θ)(cos²θ + sin²θ)/[(1 - tan²θ)(1 + tan²θ)] =
= (cos²θ - sin²θ) × 1/[(1 - tan²θ)sec²θ] (since (cos²θ + sin²θ) = 1 and 1 + tan²θ = sec²θ)
Also, Using the identity a² - b² = (a + b)(a - b), we have
(cos²θ - sin²θ) × 1/[(1 - tan²θ)sec²θ] = (cosθ - sinθ)(cosθ + sinθ)/[(1 - tanθ)(1 + tanθ)sec²θ]
= (cosθ - sinθ)(cosθ + sinθ)/[(cosθ - sinθ)/cosθ × (cosθ + sinθ)/cosθ × sec²θ]
= (cosθ - sinθ)(cosθ + sinθ)/[(cosθ - sinθ)(cosθ + sinθ)/cos²θ × 1/cos²θ]
= (cosθ - sinθ)(cosθ + sinθ)cos⁴θ/[(cosθ - sinθ)(cosθ + sinθ)]
= 1 × cos⁴θ
= cos⁴θ
So, the trigonometric identity (cos⁴θ - sin⁴θ)/(1 - tan⁴θ) = cos⁴θ
Learn more about trigonometric identities here:
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Step-by-step explanation:
Alina is building a roof for a dog house with the dimensions shown. She uses plywood to make the roof with the dimensions shown, but with an open bottom.
A net of a square pyramid has a square base with side lengths of 4 feet, and 4 triangular sides with heights of 3 feet.
Find the surface area of the roof.
The area of each triangular face is
✔ 6
ft2.
The surface area of the roof is
✔ 24
ft2.
2(x+y)=24
2x=y
Use substitution. If y=2x, than we can substitute 2x for it in the other equation, because x and y equal the same things in both equations.
So using that we get 2(x+2x)=24
SIMPLIFY
2(3x)=24
DISTRIBUTE
6x=24.
DIVIDE: x=4.
If we substitute x into the original equations we get x=4 and y=8. Those are your two numbers.
Have a nice day! :)
Answer:
This
Step-by-step explanation:
let x = rate of the slower plane (First plane!)
x+25 = rate of the faster plane (Second plane!)
The planes fly for 2 hours, where Distance = R*T
Distance between the planes = SUM of the distances.
R*T + R*T= 470 miles
2*x + 2*(x+25)=470
2x+2x + 50 = 470
4x+50=470
4x=420
x=105 mph First plane
x+25= 105+25=130 mph Second plane.
Answer:
That's it
Step-by-step explanation:
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