Angle 6 = angle 7 = 61⁰, as vertical angles
Angle 5 = angle 8, as vertical angles
angle 6+angle 7 + angle 5 + angle 8 =360
61+61 + angle 5 + angle 8 =360
angle 5 + angle 8 = 360 - 61*2 = 238⁰
Answer D. 238⁰
Answer:
x positive, y negative
Step-by-step explanation:
-60 is the 4th quadrant of the unit circle ( negative angles go clockwise from 0), so the x value is positive and the y value is negative.
Answer: Choice A
S9 = (9/2)*(2+26)
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The formula is
Sn = (n/2)*(a1+an)
where
Sn = sum of the first n terms (nth partial sum)
n = number of terms
a1 = first term
an = nth term
In this case,
n = 9
a1 = 2 (plug in n = 1 into the formula an = 3n-1 and simplify)
an = a9 = 26 (plug n = 9 into the formula an = 3n-1 and simplify)
So,
Sn = (n/2)*(a1+an)
S9 = (9/2)*(2+26)
will help us find the sum of the first 9 terms of this arithmetic sequence
