Question

h=2tcos ○÷rp check it is dimensionally correct or not?​

Answer 1

ICSE Class 9

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Sum

Evaluate :

AA

AA

cos3A–2cos4Asin3A+2sin4A , when A = 15°

SOLUTION

(i) Given that A= 15°

AA

AA

cos3A–2cos4Asin3A+2sin4A=cos(3x15°)–2cos(4x15°)sin(3x15°)+2sin(4x15°)

=

cos45°–2cos60°sin45°+2sin60°

=

12–2(12)12+2(32)

=

12–112+3

=

1–21+6

=