2. If 15 sina + 10cos^a = 6 then find the value
8 coseca +27 sec a.
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10sin4α+15cos4α=6
10(Sin4α+cos4α)+5cos4α=6
10((sin2α+cos2α)−2sin2αcos2α)±6−5cos4α
10(1−2sin2αcos2α)=6−5cos4α
4−20sin2αcos2α=−5cos4α
4sec4α−20tan2α=−5
20tan2α−4sec4α−5=0
20tan2α−4(1+tan2α)2−5=0
20tan2α−4(1+tan4α+2tan2α)−5=0
tan4α−3tan2α+49=0
(tan2α−23)2=0
tan2α=23
tanα=2
3
Now 27cosec6α+8sec6α
(3cosec2α)3+(2sec2α)3
(3×35)3+(2×25)3
125+125
=250
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