if tan a + cot a is equals to 4 then find Tan 5A + cot 5A
Answers
Answer:
tanA+cotA=4
(squaring both sides)
(tanA+cotA)2=42
⇒tan2A+cot2A+2(tanA)(cotA)=16
⇒tan2A+cot2A+2=16
⇒tan2A+cot2A=16−2
⇒tan2A+cot2A=14
(on squaring both sides)
⇒(tan2A−cot2A)2=(14)2
tan4A+cot4A+2(tan2A)(cot2A)=196
tan2A+cot4A=196−2
=194
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Answer:
If tanA+cotA=4, then what is the value of tan^6A+cot^6A?
Let tanA=a and cotA=b
Therefore, a+b = 4………(i)
ab=tanA.cotA=1…………(ii)
Therefore, (a+b)²=4²….(from i)
Therefore, a²+b²+2ab=16
Therefore, a²+b² =16–2..(from ii)
Therefore, a²+b² = 14……..(iii)
Let a²= A and b²= B
Therefore, A+B= 14(from iii)…….(iv)
Since, (A+B)³=A³+B³+3AB(A+B)
Therefore, A³+B³=(A+B)³-3AB(A+B)
Therefore, A³+B³=(14)³-3AB(14)
Therefore, A³+B³=2744–3a².b²(14)(from iv)
Therefore, (a²)³+(b²)³=2744–(ab)²42
Therefore, [(tanA)²]³+[(cotA)²]³=2744–1².42
Therefore, (tan²A)³+(cot²A)³=2744–42
Therefore, tan^6A+cot^6A=2702