Answer: Sally walked 3 minutes faster per mile
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If you're trying to find the missing side of the "triangle" (the distance from the house to where the ladder touches the ground), you would use the pythagorean theorem, a²+b²=c². (c is always hypotenuse)
a²+b²=c²
12²+b²=15²
144+b²=225
b²=81
√b²=√81
b=9
Cos9x - cos5x = -2sin2x.sin7x
sin17x - sin3x = 2sin7x.cos10x
so f(x) =

=
Answer:
The ladder is 4.86 foot from the base of the wall .
Step-by-step explanation:
Given as :
The length of the ladder = 28 ft
The ladder makes angle of 80° with the ground
Let The distance of the ladder from the foot of the wall = x ft
Now, From Triangle BAC
Cos angle = 
I.e Cos 80° = 
Or, 0.1736 = 
Or, x = 0.1736 × 28
∴ x = 4.86 foot
So, The distance of ladder from wall base = x = 4.86 foot
Hence The ladder is 4.86 foot from the base of the wall . Answer