18^ =? - Vidyadip

MCQ

$\sin 18^{\circ}=?$

A
$\frac{(\sqrt{3}+1)}{2}$
B
$\frac{(\sqrt{3}-1)}{2}$
C
$\frac{(\sqrt{5}+1)}{4}$
D
$\frac{(\sqrt{5}-1)}{4}$

✓

Answer

(d) $\frac{(\sqrt{5}-1)}{4}$
Explanation: Remember $\sin 18^{\circ}=\frac{(\sqrt{5}-1)}{4}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from Model Paper 2→Model Paper 2 — all question types→Maths STD 11 Science question papers→CBSE Board STD 11 Science question papers→CBSE Board question paper generator→

Similar questions

If $\frac{{\cos x}}{a} = \frac{{\cos (x + \theta )}}{b} = \frac{{\cos (x + 2\theta )}}{c} = \frac{{\cos (x + 3\theta )}}{d} \, ,$ then $\left( {\frac{{a + c}}{{b + d}}} \right)$ is equal to :-

If $\frac{{\tan 3\theta - 1}}{{\tan 3\theta + 1}} = \sqrt 3 $, then the general value of $\theta $ is

If the roots of the equation $a{x^2} + bx + c = 0$ are $\alpha ,\beta $, then the value of $\alpha {\beta ^2} + {\alpha ^2}\beta + \alpha \beta $ will be

In a class there are $18$ boys who are over $160 \ cm$ tall If these constitute three$-$fourths of the boys and the total number of boys is tow$-$third of the total number of students in the class what is the number of girls in the class?

$\lim _{x \rightarrow 0}\left(\frac{(x+2 \cos x)^{3}+2(x+2 \cos x)^{2}+3 \sin (x+2 \cos x)}{(x+2)^{3}+2(x+2)^{2}+3 \sin (x+2)}\right)^{\frac{100}{x}}$is equal to$.....$

A hyperbola passes through the points $(3, 2)$ and $(-17, 12)$ and has its centre at origin and transverse axis is along $x$ - axis. The length of its transverse axis is

Let $x_1, x_2, ... x_n$ be n observations. Let $w_i = lx_i + k for i = 1, 2, ... n,$ where l and k are constants. If the mean of $\text{x}_\text{i}{'\text{s}}$ is $48$ and their standard deviation is $12,$ the mean of $\text{w}_\text{i}{'\text{s}}$ is $55$ and standard deviation of $\text{w}_\text{i}{'\text{s}}$ is $15,$ the values of l and $k$ should be:

Number of integral points interior to the circle $x^2 + y^2 = 10$ from which exactly one real tangent can be drawn to the curve $\sqrt {{{\left( {x + 5\sqrt 2 } \right)}^2} + {y^2}} \, - \sqrt {{{\left( {x - 5\sqrt 2 } \right)}^2} + {y^2}\,} \, = 10$ are (where integral point $(x, y)$ means $x, y \in I)$

Let $f(x) = Ax^3 -Bx -tanx.sgn(x)$ be an even function $\forall \,\,x\, \in R - \left\{ {\left( {2n + 1} \right)\frac{\pi }{2},n \in I} \right\}$ ,

where $A = {\sin ^2}\alpha - \sin \alpha + \frac{1}{4}$

and $B = {\tan ^2}\alpha + \frac{2}{{\sqrt 3 }}\tan \alpha + \frac{1}{3}$ , then the number of value $(s)$ of $\alpha $ in $\left[ { - \frac{{3\pi }}{2},2\pi } \right]$ is - (where $sgnx$ denotes signum function of $x$ )

In a rectangle $A B C D$, the coordinates of $A$ and $B$ are $(1,2)$ and $(3,6)$ respectively and some diameter of the circumscribing circle of $A B C D$ has equation $2 x-y+4=0$. Then, the area of the rectangle is