The answer would have to be D.
A and 90-a is the measure of the two angles
a=90-a-6
2a=84
a=42
42° and 48°
(a)

Substitute <em>x</em> = 3 tan(<em>t</em> ) and d<em>x</em> = 3 sec²(<em>t </em>) d<em>t</em> :


(b) The series

converges by comparison to the convergent <em>p</em>-series,

(c) The series

converges absolutely, since

That is, ∑ (-1)ⁿ (<em>n</em> ² + 9)/<em>e</em>ⁿ converges absolutely because ∑ |(-1)ⁿ (<em>n</em> ² + 9)/<em>e</em>ⁿ| = ∑ (<em>n</em> ² + 9)/<em>e</em>ⁿ in turn converges by comparison to a geometric series.
The formula to find the area of a triangle is

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