4 years ago

What is the sum of the arithmetic series below?

1 answer:

7 0

When we substitute the initial values of i, we find that the series is:
3, 5, 7, 9 ...
This means it is an arithmetic progression with the first term being 3 and the common difference being 2. We have to find the sum of the first 18 terms. Using the formula:

Sn = n/2[2a + (n - 1)d]
S₁₈ = 18/2[2(3) + (18 - 1)2]
S₁₈ = 360

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Solve tan x - cot x = -2cos 2x cosec 2x

ololo11 [35]

Answer:

Step-by-step explanation:

tan x-cot x

$=\frac{sin~x}{cos~x} -\frac{cos~x}{sin ~x} \\=\frac{sin^2x-cos^2 x}{sin ~x~cos~x} \\=\frac{-2(cos^2x-sin^2x)}{2 sin ~x~cos~x} \\=\frac{-2 cos~2x}{sin~2x} \\=-2 cos ~2x~cosec~2x$