write an application to the principal of your school requesting her to remit your fine for being absent from school
Answers
The Principal
_______High School
New Delhi
110045
Date- ___________
Subject- Application to remit the fine.
Sir,
With due respect, I, XYZ, the student of standard 6, section 'B' of your school want to beg to you to remit my fine. I've been fined because I went absent for a week. The reason for my absence was that I lost my grandfather and hence my whole family had to depart. I hope that you'll consider my request and remit my fine.
Thanking you in anticipation.
Yours truly
_______
Class__,Section
_______ High School
forumlas used ;
cos (π/2- X) = cos X
Sin (π/2- X) = sinx
sinx²+ cos x²= 1
and 2 sin A sin B = sin (A+B) + sin ( A-B)
❇️step by step explanation
cos³(π/8) cos( 3π/8)
+ sin ³(π/8) sin ( 3π/8)
= cos ³(π/8) cos (π/2 - π/8) +
sin³(π /8) sin (π/2- π/8)
= cos³(π/8) sin ( π/8)
+ sin ³(π/8) cos ( π/8)
= sin (π /8) cos (π /8) [ sin²(π/8) + cos²( π/8) ]
{ since sin x² + cos x²= 1 }
then ,
= sin (π/8) cos (π/8)
multiply and divide by 2
=
\frac{1}{2} (2 \sin( \frac{\pi}{8} ) \cos( \frac{\pi}{8} )
2
1
(2sin(
8
π
)cos(
8
π
)
now use formula
[ 2 sin A sin B = sin (A+B) + sin ( A-B)]
then , we get
=
= \frac{1}{2} ( \sin( \frac{\pi}{4} ) \times \sin(0) )=
2
1
(sin(
4
π
)×sin(0))
= \frac{1}{2 \sqrt{2} }=
2
2
1
• so the value of
cos³(π/8) cos( 3π/8)
+ sin ³(π/8) sin ( 3π/8) = 1/(2√ 2)
I hope it helps you
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