Hank estimated the width of the door to his classroom in feet. What is a reasonable estimate?
1 answer:
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Answer:
y = -(5/2)x -2
Explanation:
The general formula for a straight line is y – mx + b.
The image below shows the graph of the line.
Step 1. <em>Calculate the slope</em>.
Slope = m = Δy/Δx = (y₂-y₁)/(x₂-x₁)
x₁ = 0; y₁ = -2
x₂ = -2; y₂ = 3 Calculate m
m = [3-(-2)]/(-2-0)
m = (3+2)/(-2)
m = 5/(-2)
m = -5/2
Step 2. <em>Calculate the y-intercept </em>
When x = 0, y = 2.
The y-intercept (b) is at y = -2
Step 3. <em>Write the equation </em>for the graph
y = mx + b
y = -(5/2)x - 2
Answer:
- cos(2θ) = 7/25
- tan(2θ) = -24/7
Step-by-step explanation:
Sometimes, it is easiest to let a calculator do the work. (See below)
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The magnitude of the tangent is less than 1, so the reference angle will be less than 45°. Then double the angle will be less than 90°, so will remain in the 4th quadrant, where the cosine is positive and the tangent is negative.
You can also use the identities ...
cos(2θ) = (1 -tan(θ)²)/(1 +tan(θ)²)
cos(2θ) = (1 -(-3/4)²)/(1 +(-3/4)²) = ((16-9)/16)/((16+9)/16)
cos(2θ) = 7/25
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tan(2θ) = 2tan(θ)/(1 -tan(θ)²) = 2(-3/4)/((16-9/16) = (-6/4)(16/7)
tan(2θ) = -24/7
