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Understanding Elementary Shapes | Exercise 5.2

Question 12

Find the number of right angles turned through by the hour hand of a clock when it goes from

(a) 3 to 6

(b) 2 to 8

(c) 5 to 11

(d) 10 to 1

(e) 12 to 9

(f) 12 to 6

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  • Solution

  • Transcript

The hour hand of a clock revolves by 360° or it covers 4 right angles in one complete revolution

(a) If hour hand of a clock goes from 3 to 6, it revolves by 90° or 1 right angle

(b) If hour hand of a clock goes from 2 to 8, it revolves by 180°or 2 right angles

(c) If hour hand of a clock goes from 5 to 11, it revolves by 180°or 2 right angles

(d) If hour hand of a clock goes from 10 to 1, it revolves by 90° or 1 right angle

(e) If hour hand of a clock goes from 12 to 9, it revolves by 2700 or 3 right angles

(f) If hour hand of a clock goes from 12 to 6, it revolves by 180° or 2 right angles

"hello students welcome to lido homework i am tutor aaron swathi from lido learning now let us simplify the following expressions we have 5 expressions we will take them separately and simplify it so i'll take the first one which is 11 plus root 11 into 11 minus root 11 so both the expressions are the same but the sign is alone only different so we could relate this with the identity a plus b into a minus b which will be a square minus b square so now we are going to make use of this identity so now this becomes 11 square minus root of 11 square we know that 11 square is 121 root 11 into root 11 is 11. so minus 11. so 121 minus 11 will be 1 now we have got our simplified form therefore the simplified form of 11 plus root 11 into 11 minus root 11 is one thing now we'll go to our second part of the question 5 plus root 7 into 5 minus root 7 here it is same as a plus b into a minus b so we could write this as pi square minus root 7 the whole square so 5 square is 25 minus root 7 into root 7 will be 7 so which is equal to 18 so therefore the simplified form of 5 plus root 7 into 5 minus root 7 is equal to 18 now we will go for the third part of the question the third one is root 8 minus root 2 into root 8 plus root 2. so here it is in the form of a minus b into a plus b however both are the same so it will also be a square minus b square so we could write this as root 8 square minus root 2 square so root 8 into root 8 will be 8 and root 2 into root 2 is 2 which is equal to 6 therefore the simplified form of root 8 minus root 2 into root 8 plus root 2 is equal to 6 now we'll go for the fourth question which is 3 plus root 3 into 3 minus root 3 same a plus b into a minus b 4 we know it will be 3 square minus root 3 square so 3 square is 9 and root 3 into root 3 is 3 so 3 therefore we could tell 9 minus 3 is 6 therefore the simplified form of 3 plus root 3 into 3 minus root 3 is equal to 6 now we will go for the fifth question which is root 5 minus root 2 into root 5 plus root 2 so it is also in the form of a minus b into a plus b so the answer will be root 5 square minus root 2 square root 5 into root pi is 5 and root 2 into root 2 will be so it is equal to 3 therefore the simplified form of root 5 minus root 2 into root 5 plus root 2 is equal to 3 so in all these expressions we used only one identity which was a minus b into a plus b which was a square minus b square if you have any doubts please post your questions in the comment box and subscribe the channel for regular updates thank you"

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Question 12

Find the number of right angles turned through by the hour hand of a clock when it goes from

(a) 3 to 6

(b) 2 to 8

(c) 5 to 11

(d) 10 to 1

(e) 12 to 9

(f) 12 to 6

  • Solution

  • Transcript

The hour hand of a clock revolves by 360° or it covers 4 right angles in one complete revolution

(a) If hour hand of a clock goes from 3 to 6, it revolves by 90° or 1 right angle

(b) If hour hand of a clock goes from 2 to 8, it revolves by 180°or 2 right angles

(c) If hour hand of a clock goes from 5 to 11, it revolves by 180°or 2 right angles

(d) If hour hand of a clock goes from 10 to 1, it revolves by 90° or 1 right angle

(e) If hour hand of a clock goes from 12 to 9, it revolves by 2700 or 3 right angles

(f) If hour hand of a clock goes from 12 to 6, it revolves by 180° or 2 right angles

"hello students welcome to lido homework i am tutor aaron swathi from lido learning now let us simplify the following expressions we have 5 expressions we will take them separately and simplify it so i'll take the first one which is 11 plus root 11 into 11 minus root 11 so both the expressions are the same but the sign is alone only different so we could relate this with the identity a plus b into a minus b which will be a square minus b square so now we are going to make use of this identity so now this becomes 11 square minus root of 11 square we know that 11 square is 121 root 11 into root 11 is 11. so minus 11. so 121 minus 11 will be 1 now we have got our simplified form therefore the simplified form of 11 plus root 11 into 11 minus root 11 is one thing now we'll go to our second part of the question 5 plus root 7 into 5 minus root 7 here it is same as a plus b into a minus b so we could write this as pi square minus root 7 the whole square so 5 square is 25 minus root 7 into root 7 will be 7 so which is equal to 18 so therefore the simplified form of 5 plus root 7 into 5 minus root 7 is equal to 18 now we will go for the third part of the question the third one is root 8 minus root 2 into root 8 plus root 2. so here it is in the form of a minus b into a plus b however both are the same so it will also be a square minus b square so we could write this as root 8 square minus root 2 square so root 8 into root 8 will be 8 and root 2 into root 2 is 2 which is equal to 6 therefore the simplified form of root 8 minus root 2 into root 8 plus root 2 is equal to 6 now we'll go for the fourth question which is 3 plus root 3 into 3 minus root 3 same a plus b into a minus b 4 we know it will be 3 square minus root 3 square so 3 square is 9 and root 3 into root 3 is 3 so 3 therefore we could tell 9 minus 3 is 6 therefore the simplified form of 3 plus root 3 into 3 minus root 3 is equal to 6 now we will go for the fifth question which is root 5 minus root 2 into root 5 plus root 2 so it is also in the form of a minus b into a plus b so the answer will be root 5 square minus root 2 square root 5 into root pi is 5 and root 2 into root 2 will be so it is equal to 3 therefore the simplified form of root 5 minus root 2 into root 5 plus root 2 is equal to 3 so in all these expressions we used only one identity which was a minus b into a plus b which was a square minus b square if you have any doubts please post your questions in the comment box and subscribe the channel for regular updates thank you"

Our top 5% students will be awarded a special scholarship to Lido.

subject-cta
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