KCET · Maths · Trigonometric Ratios & Identities
The value of \(\sin 10^{\circ} \cdot \sin 30^{\circ} \cdot \sin 50^{\circ} \cdot \sin 70^{\circ}\) is
- A \(\frac{1}{8}\)
- B \(\frac{3}{16}\)
- C \(\frac{\sqrt{3}}{16}\)
- D \(\frac{1}{16}\)
Answer & Solution
Correct Answer
(D) \(\frac{1}{16}\)
Step-by-step Solution
Detailed explanation
\(\begin{aligned} \sin 10^{\circ} \cdot & \sin 30^{\circ} \cdot \sin 50^{\circ} \cdot \sin 70^{\circ} \\ &=\frac{1}{2} \cdot \sin 10^{\circ} \cdot \frac{1}{2}\left(2 \sin 70^{\circ} \cdot \sin 50^{\circ}\right) \\ &=\frac{1}{2} \sin 10^{\circ} \cdot \frac{1}{2}\left\{\cos \left(70^{\circ}-50^{\circ}\right)\right.\\ &=\frac{1}{2} \sin 10^{\circ} \cdot \frac{1}{2}\left\{\cos \left(70^{\circ}+50^{\circ}\right)\right\} \\ &=\frac{1}{2} \sin 10^{\circ} \cdot \frac{1}{2}\left(\cos 10^{\circ}+\frac{1}{2}\right) \\ &=\frac{1}{4} \sin 10^{\circ} \cdot \cos 20^{\circ}+\frac{1}{8} \sin 10^{\circ} \\ &=\frac{1}{4} \cdot \frac{1}{2}\left(\sin 30^{\circ}-\sin 10^{\circ}\right)+\frac{1}{8} \cdot \sin 10^{\circ} \\ &=\frac{1}{8} \cdot \sin 30^{\circ}-\frac{1}{8} \sin 10^{\circ}+1 / 8 \sin 10^{\circ} \\ &=\frac{1}{8} \cdot \frac{1}{2}-0=\frac{1}{16} \end{aligned}\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Maths
- A particle moves along the curve \(\frac{x^2}{16}+\frac{y^2}{4}=1\). When the rate of change of abscissa is 4 times that of its ordinate, then the quadrant in which the particle lies isKCET 2023 Easy
- The value of \(\int \frac{1}{1+\cos 8 x} d x\) isKCET 2007 Easy
- The ninth term of the expansion \(\left(3 x-\frac{1}{2 x}\right)^{8}\) isKCET 2007 Easy
- \( \int_{-3}^{3} \cot ^{-1} x d x= \)KCET 2019 Medium
- If \( |\bar{a} \times \bar{b}|^{2}+|\bar{a} \cdot \bar{b}|^{2}=144 \) and \( |\bar{a}|=4 \), then the value of \( |\bar{b}| \) isKCET 2018 Hard
- \(\lim _{x \rightarrow 0} \frac{\log _{e}(1+x)}{3^{x}-1}\) is equal toKCET 2013 Easy
More PYQs from KCET
- The rate constant \(k_1\) and \(k_2\) for two different reactions are \(10^{16} \times e^{-2000 / T}\) and \(10^{15} \times e^{-1000 / T}\) respectively. The temperature at which \(k_1=k_2\) isKCET 2023 Medium
- \(\int e^{x}\left[\frac{\sin x+\cos x}{1-\sin ^{2} x}\right] d x\) isKCET 2011 Medium
- What is the de Broglie wavelength of the electron accelerated through a potential difference of
\( 100 \) Volt?KCET 2014 Easy - If \(|\mathbf{a}+\mathbf{b}|=|\mathbf{a}-\mathbf{b}|\), thenKCET 2023 Easy
- \( \lim _{x \rightarrow 0} \frac{1-\cos x}{x^{2}} \) isKCET 2015 Hard
- The electric field and the potential of an electric dipole vary with distance \(r\) asKCET 2022 Easy