You are in the electronics store purchasing a video game that retails for 45$ the sales tax charged on the game is 2.70 what is
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The distance traveled by Davis family = 35 miles
Time taken to cover the distance = hour
Speed = Distance Time
Speed =
Speed =
So, speed = 70 miles/hour.
At 2:00 pm, the family destination was 245 miles away.
So, the number of hours, when the family was 245 miles away =
= 3.5 hours
So, after 3.5 hours, that is at 5:30 pm, the Davis family will be 245 miles away.
Recall the angle sum identities:
cos(a + b) = cos(a) cos(b) - sin(a) sin(b)
cos(a - b) = cos(a) cos(b) + sin(a) sin(b)
sin(a + b) = sin(a) cos(b) + sin(b) cos(a)
sin(a - b) = sin(a) cos(b) - sin(b) cos(a)
Notice that adding the first two together, and subtract the last from the third, we get two more identities:
cos(a + b) + cos(a - b) = 2 cos(a) cos(b)
sin(a + b) + sin(a - b) = 2 sin(b) cos(a)
Let a = 4x and b = x. Then
cos(5x) + cos(3x) = 2 cos(4x) cos(x)
sin(5x) - sin(3x) = 2 sin(x) cos(4x)
Now,
as required.