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Answer:
y = 1 +4√2
Step-by-step explanation:
The hints can be useful here.
At x=0, the equation becomes ...
y = a·cos(0) +b = a + b = 9
At x = 90°, the equation becomes ...
y = a·cos(90°) +b = b = 1
Then the value of 'a' is ...
a +1 = 9 ⇒ a = 8
and the equation for y is ...
y = 8·cos(x) +1
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For x = 45°, this is ...
y = 8·(√2/2) +1 = 1 +4√2
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Your short table of trig function values will tell you cos(45°) = (√2)/2.
