Introduction of Trigonometry — Maths STD 10 — Question
CBSE BoardEnglish MediumSTD 10MathsIntroduction of Trigonometry1 Mark
MCQ
The value of $\cos1^\circ\cos2^\circ\cos3^\circ.....\cos180^\circ$ is :
A
$1$
✓
$0$
C
$-1$
D
None of these
✓
Answer
Correct option: B.
$0$
Here we have to find : $\cos1^\circ\cos2^\circ\cos3^\circ.....\cos180^\circ$
$\cos1^\circ\cos2^\circ\cos3^\circ.....\cos180^\circ$
$=\cos1^\circ\cos2^\circ\cos3^\circ...\cos89^\circ\cos90^\circ\cos91^\circ...\cos180^\circ$
$[\text{since} \cos90^\circ=0]$
$=\cos1^\circ\cos2^\circ\cos3^\circ...0\times\cos90^\circ...\cos180^\circ$
$=0$
Hence the correct option is $(b)$
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