sin^2 24° - sin^26° = (√5 - 1)/8
Answers
Answer:
√5-1
-------------
8
Step-by-step explanation:
I think there is a mistake in question
question is like this
√5-1
sin²24*-sin²6*=------------
8
now
L. H. S. =sin²24*-sin²6*
we have a identity
sin²A-sin²B=sin(A+B) sin(A-B)
applying this
=sin(24*+6*) sin (24*-6*)
=sin 30* sin 18*
we know that
1 √5-1
sin 30*=----- and sin18*= ----------
2 4
putting these values
1 √5-1
=--------- ---------------
2 4
√5-1
=---------------=RHS
8
additional information----->
______________________
√(10+2√5)
cos18*=-----------------
4
√5-1
sin72* = -------------
4
√5+1
cos36*=-------------
4
√10-2√5
sin 36*= --------------
4
Hope it helps you
have a nice day
To prove -
sin²24° - sin²6° = (√5-1)/8
Solution -
LHS
As we know that
sin²a - sin²b = sin(a+b)sin(a-b)
Then , sin(24+6)sin(24-6)
→sin 30° .sin18°
→ sin 30 = 1/2 and
LHS= RHS
hence proved
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