Evaluate the value of $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$.
Answer
651k+ views
Hint: Start by writing down the given equation . Try to recall all the values of trigonometric ratios for corresponding angles and substitute in the given equation. Simplify the equation in order to get the desired value for the given equation.
Complete step-by-step answer:
Given,
$\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$
Step by step complete solution
We know the values of following trigonometric ratios
From the above table we get
$\sin {60^ \circ } = \dfrac{{\sqrt 3 }}{2}$ and $\sin {30^ \circ } = \dfrac{1}{2}$
$\cos {30^ \circ } = \dfrac{{\sqrt 3 }}{2}$ and $\cos {60^ \circ } = \dfrac{1}{2}$
Substituting these values in the relation we get
$
\Rightarrow \sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ } \\
\Rightarrow \dfrac{{\sqrt 3 }}{2} \times \dfrac{{\sqrt 3 }}{2} + \dfrac{1}{2} \times \dfrac{1}{2} \\
\\
$
We know $\sqrt 3 \times \sqrt 3 = {(\sqrt 3 )^2} = 3$
Similarly in denominator ,we have $2 \times 2 = {(2)^2} = 4$
$ = \dfrac{3}{4} + \dfrac{1}{4}$
Taking 4 as L.C.M. , we get
$
= \dfrac{4}{4} \\
= 1 \\
$
So , the value of $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$ is 1.
Note: Students must remember all the trigonometric values of different angles , which are used more often. Attention must be given while substituting the values , keeping in mind the quadrant system, here we had all the positive values only , But one might get different quadrant values as well.
Alternative method:-
We can simplify the given trigonometric equation by using trigonometric formulas
We have $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$
This is of the form $\sin A\cos B + \cos A\sin B$
And we know $\sin (A + B) = \sin A\cos B + \cos A\sin B$
So our equation $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$would become
$\sin {(60 + 30)^ \circ } = \sin {90^ \circ }$
And we know the value of $\sin {90^ \circ } = 1$from the table of trigonometric values for different angles.
Therefore , the value of $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$ is 1.
Complete step-by-step answer:
Given,
$\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$
Step by step complete solution
We know the values of following trigonometric ratios
| $\theta $ | ${0^ \circ }$ | ${30^ \circ }$ | ${45^ \circ }$ | ${60^ \circ }$ | ${90^ \circ }$ |
| $\sin \theta $ | $0$ | $\dfrac{1}{2}$ | $\dfrac{1}{{\sqrt 2 }}$ | $\dfrac{{\sqrt 3 }}{2}$ | $1$ |
| $\cos \theta $ | $1$ | $\dfrac{{\sqrt 3 }}{2}$ | $\dfrac{1}{{\sqrt 2 }}$ | $\dfrac{1}{2}$ | $0$ |
From the above table we get
$\sin {60^ \circ } = \dfrac{{\sqrt 3 }}{2}$ and $\sin {30^ \circ } = \dfrac{1}{2}$
$\cos {30^ \circ } = \dfrac{{\sqrt 3 }}{2}$ and $\cos {60^ \circ } = \dfrac{1}{2}$
Substituting these values in the relation we get
$
\Rightarrow \sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ } \\
\Rightarrow \dfrac{{\sqrt 3 }}{2} \times \dfrac{{\sqrt 3 }}{2} + \dfrac{1}{2} \times \dfrac{1}{2} \\
\\
$
We know $\sqrt 3 \times \sqrt 3 = {(\sqrt 3 )^2} = 3$
Similarly in denominator ,we have $2 \times 2 = {(2)^2} = 4$
$ = \dfrac{3}{4} + \dfrac{1}{4}$
Taking 4 as L.C.M. , we get
$
= \dfrac{4}{4} \\
= 1 \\
$
So , the value of $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$ is 1.
Note: Students must remember all the trigonometric values of different angles , which are used more often. Attention must be given while substituting the values , keeping in mind the quadrant system, here we had all the positive values only , But one might get different quadrant values as well.
Alternative method:-
We can simplify the given trigonometric equation by using trigonometric formulas
We have $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$
This is of the form $\sin A\cos B + \cos A\sin B$
And we know $\sin (A + B) = \sin A\cos B + \cos A\sin B$
So our equation $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$would become
$\sin {(60 + 30)^ \circ } = \sin {90^ \circ }$
And we know the value of $\sin {90^ \circ } = 1$from the table of trigonometric values for different angles.
Therefore , the value of $\sin {60^ \circ }\cos {30^ \circ } + \cos {60^ \circ }\sin {30^ \circ }$ is 1.
Recently Updated Pages
If x a + bt + ct2 where x is in meters and t is in class 11 physics CBSE

A car covers the first half distance between two places class 11 physics CBSE

The resultant of two vectors overrightarrow P and overrightarrow class 11 physics CBSE

Find the value of cos 135 class 11 maths CBSE

A mass M is held in place by an applied force F and class 11 physics CBSE

A solution of glucose in water is labelled as 10 dfracwv class 11 chemistry CBSE

Trending doubts
One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE

Find the value of the expression given below sin 30circ class 11 maths CBSE

Draw a diagram of nephron and explain its structur class 11 biology CBSE

10 examples of friction in our daily life

Proton was discovered by A Thomson B Rutherford C Chadwick class 11 chemistry CBSE

Bond order ofO2 O2+ O2 and O22 is in order A O2 langle class 11 chemistry CBSE

