Q. 8cos^3(20) - 8sin^3(10) - 6cos20 + 6sin10 = 2
S.E.E. Solution
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Soln: L.H.S. = 8cos 3 20 – 8sin 3 10 – 6cos20 + 6sin10 = 2(4cos 3 20 – 4sinn 3 10 – 3cos20 + 3sin10) = 2(4cos 3 20 - 3cos20 +...
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Q. Prove that : tan20 + 4sin20 = root 3
Soln:
L.H.S.
= tan20 + 4sin20
= sin20/cos20 + 4sin20
= (sin20 + 4sin20.cos20)/(cos20)
= (sin20 + 2sin40)/cos20
= [sin20 + ... 
Q. cosec40 - root(3)sec40 = 4cot100
Soln:
L.H.S.
= cosec40 - Ö3sec40
= 1/sin40 - Ö3/cos40
= 1/sin40 -
tan60/cos40 [tan60=Ö3]
= 1/sin40 -
si ... Prove that: [tan(alpha)+sec(alpha)-1]/[tan(alpha)-sec(alpha)+1] = [1+sin(alpha)]/cos(alpha)
Soln
... Q. Prove that: (cos5a.sin2a-cos4a.sin3a)/(sin5a.sin2a-cos4a.cos3a) = cot2a
Soln:
L.H.S.
= (cos5a.sin2a-cos4a.sin3a)/(sin5a.sin2a-cos4a.cos3a)
Multiply numerator and denominator by 2.
= 2(cos5a.sin2a - ... Prove that: (2cosA + 1)(2cosA - 1)(2cos2A - 1) = 2cos4A + 1
Soln:
... A complete solution for SEE students.
