Directions: Divide the array in 2 smaller facts to help you fill in the
1 answer:
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Answer:
S₁₅ = 645
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
=
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Using the nth term formula = 5n + 3 , then
a₁ = 5(1) + 3 = 5 + 3 = 8
a₂ = 5(2) + 3 = 10 + 3 = 13 , then
d = a₂ - a₁ = 13 - 8 = 5
Thus
S₁₅ = [ (2 × 8) + (14 × 5) ]
= 7.5( 16 + 70)
= 7.5 × 86
= 645
Answer:
-5/13
Step-by-step explanation:
sin theta = opp / hyp
sin theta = -12 /13
we can find the adj side by using the pythagorean theorem
adj^2 + opp ^2 = hyp^2
adj^2 +(-12)^2 = 13^2
adj^2 +144 =169
adj^2 = 169-144
adj^2 = 25
Taking the square root of each side
adj = ±5
We know that it has to be negative since it is in the third quad
adj = -5
cos theta = adj / hyp
cos theta = -5/13
