Find the angle between hour-hand and minute-hand in a clock at
A) Ten past eleven
B) Twenty past seven
C) Thirty-five past one
D) Quarter to six
E) \[2:20\]
F) \[10:10\]
Answer
646.8k+ views
Hint:
Here we are asked to find the angle between hour hand and minute hand for some given values of time.
So, firstly we will find the numbers where the hour hand and minute hand are pointing and note the numbers.
Thus, we will put the value of h and m in the equation $\left| {30h - \dfrac{{11}}{2}m} \right|$ .
Hence, we get the required answers.
Complete step by step solution:
To find the angle between minute hand and hour hand we have to apply formula
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
Where h denotes hour and m denotes minutes.
Ten past eleven means = 11:10 pm
Where \[h = 11\] , \[m = 10\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle \[ = \left| {30 \times 11 - \dfrac{{11}}{2} \times 10} \right|\]
\[ = \left| {330 - 55} \right|\]
$ = {275^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${275^ \circ }$
Twenty past seven means = 7:20
Where \[h = 7,m = 20\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$ .
By using above formula,
Angle $ = \left| {30 \times 7 - \dfrac{{11}}{2} \times 20} \right|$
$ = \left| {210 - 110} \right|$
$ = {100^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${100^ \circ }$
Thirty-five past one means \[ = {\text{ }}1:3\]
Where \[h = 1,m = 35\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 1 - \dfrac{{11}}{2} \times 35} \right|$
$ = \left| {30 - 192.5} \right|$
$ = {162.5^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${162.5^ \circ }$
Quarter to six means \[ = 5:45\]
Where \[h = 5,m = 45\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 5 - \dfrac{{11}}{2} \times 45} \right|$
$ = \left| {150 - 247.5} \right|$
$ = {97.5^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${97.5^ \circ }$
\[2:20\]
Where \[h = 2,m = 20\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 2 - \dfrac{{11}}{2} \times 20} \right|$
$ = \left| {60 - 110} \right|$
$ = {50^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${50^ \circ }$
\[10:10\]
Where \[h = 10,m = 10\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 10 - \dfrac{{11}}{2} \times 10} \right|$
$ = \left| {300 - 55} \right|$
$ = {245^ \circ }$
Angle between hour hand and minute hand is ${245^ \circ }$
Note:
The above question can solve with alternate method,
Since, the above question can solve with another formula also i.e.
\[
\Delta \theta = \left| {{\theta _{hr}} - {\theta _{\min }}} \right| \\
\Delta \theta = \left| {0.5^\circ \times \left( {60 \times H + M} \right) - 6^\circ \times M} \right| \\
\Delta \theta = \left| {0.5^\circ \times \left( {60 \times H + M} \right) - 0.5^\circ \times 12 \times M} \right| \\
\Delta \theta = \left| {0.5^\circ \times \left( {60 \times H - 11 \times M} \right)} \right| \\
\]
Where, H is the hour and M is the minute
Since, if the angle is greater than $180^\circ $ then subtract It from $360^\circ $ .
Here we are asked to find the angle between hour hand and minute hand for some given values of time.
So, firstly we will find the numbers where the hour hand and minute hand are pointing and note the numbers.
Thus, we will put the value of h and m in the equation $\left| {30h - \dfrac{{11}}{2}m} \right|$ .
Hence, we get the required answers.
Complete step by step solution:
To find the angle between minute hand and hour hand we have to apply formula
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
Where h denotes hour and m denotes minutes.
Ten past eleven means = 11:10 pm
Where \[h = 11\] , \[m = 10\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle \[ = \left| {30 \times 11 - \dfrac{{11}}{2} \times 10} \right|\]
\[ = \left| {330 - 55} \right|\]
$ = {275^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${275^ \circ }$
Twenty past seven means = 7:20
Where \[h = 7,m = 20\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$ .
By using above formula,
Angle $ = \left| {30 \times 7 - \dfrac{{11}}{2} \times 20} \right|$
$ = \left| {210 - 110} \right|$
$ = {100^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${100^ \circ }$
Thirty-five past one means \[ = {\text{ }}1:3\]
Where \[h = 1,m = 35\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 1 - \dfrac{{11}}{2} \times 35} \right|$
$ = \left| {30 - 192.5} \right|$
$ = {162.5^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${162.5^ \circ }$
Quarter to six means \[ = 5:45\]
Where \[h = 5,m = 45\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 5 - \dfrac{{11}}{2} \times 45} \right|$
$ = \left| {150 - 247.5} \right|$
$ = {97.5^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${97.5^ \circ }$
\[2:20\]
Where \[h = 2,m = 20\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 2 - \dfrac{{11}}{2} \times 20} \right|$
$ = \left| {60 - 110} \right|$
$ = {50^ \circ }$
$ \Rightarrow $ Angle between hour hand and minute hand is ${50^ \circ }$
\[10:10\]
Where \[h = 10,m = 10\]
$ = \left| {30h - \dfrac{{11}}{2}m} \right|$
By using above formula,
Angle $ = \left| {30 \times 10 - \dfrac{{11}}{2} \times 10} \right|$
$ = \left| {300 - 55} \right|$
$ = {245^ \circ }$
Angle between hour hand and minute hand is ${245^ \circ }$
Note:
The above question can solve with alternate method,
Since, the above question can solve with another formula also i.e.
\[
\Delta \theta = \left| {{\theta _{hr}} - {\theta _{\min }}} \right| \\
\Delta \theta = \left| {0.5^\circ \times \left( {60 \times H + M} \right) - 6^\circ \times M} \right| \\
\Delta \theta = \left| {0.5^\circ \times \left( {60 \times H + M} \right) - 0.5^\circ \times 12 \times M} \right| \\
\Delta \theta = \left| {0.5^\circ \times \left( {60 \times H - 11 \times M} \right)} \right| \\
\]
Where, H is the hour and M is the minute
Since, if the angle is greater than $180^\circ $ then subtract It from $360^\circ $ .
Recently Updated Pages
Write any three differences between metals and nonmetals class 10 social science CBSE

Amit standing on a horizontal plane finds a bird flying class 10 maths CBSE

Two circles of radii 5 cm and 3 cm intersect at two class 10 maths CBSE

Solve the following i John and Jivanti together have class 10 maths CBSE

What is the relation between orthocenter circumcentre class 10 maths CBSE

Two plane mirrors are inclined at 70circ A ray incident class 10 physics CBSE

Trending doubts
Explain the Treaty of Vienna of 1815 class 10 social science CBSE

1 GB equals how many MB?

10 examples of evaporation in daily life with explanations

What is the full form of POSCO class 10 social science CBSE

Which is the hottest planet in the Solar system A Earth class 10 social science CBSE

Name any four life processes in living things class 10 biology CBSE

