Answer: The answer is 381.85 feet.
Step-by-step explanation: Given that a window is 20 feet above the ground. From there, the angle of elevation to the top of a building across the street is 78°, and the angle of depression to the base of the same building is 15°. We are to calculate the height of the building across the street.
This situation is framed very nicely in the attached figure, where
BG = 20 feet, ∠AWB = 78°, ∠WAB = WBG = 15° and AH = height of the bulding across the street = ?
From the right-angled triangle WGB, we have

and from the right-angled triangle WAB, we have'

Therefore, AH = AB + BH = h + GB = 361.85+20 = 381.85 feet.
Thus, the height of the building across the street is 381.85 feet.
For this case we have that by definition it is fulfilled:

Where:
a: It is the base
b: It is the exponent
So, if we have the following expression:
-6 to the power of 4, is equivalent to: 
So we have to:
-6: It is the base
4: It is the exponent
Answer:
-6: It is the base
4: It is the exponent
Answer:
equation for line: y = 5/3x -7/3
Step-by-step explanation:
The equation for a linear line is y = mx + c. m is the gradient of the line, also known as slope. So, m = 5/3.
Next we need to find c. Since we know a point the line must intersect, we can sub this into our line equation to get an answer:
(2,1) x=2,y=1
1 = 5/3*2 + c
1 = 10/3 + c
1 - 10/3 = c
3/3 - 10/3 = c
-7/3 = c
The final eqaution of the line is: y = 5/3x -7/3
Plug in 4 for x and solve equation like so. c=2
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