# maths

posted by .

1 at what time betweeen 7o'clock and 8o'clock will the hands of a watch be at right angles (for the first time)
2 the floor of a room is in the form of a rectangle 'x'cm long and 'y'cm broad but with one corner rounded off by a quadrant of a circle of radius 'r' ,'r' bieng less than both x and y show that the area of the floor is given by A=xy-(1-22/7/4)r^2

• maths -

1.) 7:15

• maths -

Danny's answer is not correct, (just look at the angle at 7:15)
After 7:00 ....
When the minute hand has moved x°, the hour hand is at 210 + x/60

210 + x/60 - x = 90
12600 + x - 60x = 5400
-59x = -7200
x = 122.0338° or 20.34 minutes, 20 minutes + appr 20 seconds

so the time is 7:20:20

## Similar Questions

1. ### math

At what time between 6 o’clock and 7 o’clock will the hands on a clock be together?
2. ### math

At what times between 6 o’clock and 7 o’clock will the hands on a clock be at a right angle?
3. ### Algebra

At a certain time, Janice notices that her digital watch reads (a) minutes after two o'clock. Fifteen minutes later, it reads (b) minutes after three o'clock. She is amused to note that (a) is six times greater than (b). What time …
4. ### Differential Calculus

A clock has hands 1 and 1 3/5 inches long respectively. At what rate are the ends of the hands approaching each other when the time is 2 o'clock?
5. ### Physics

Any help is appreciated! A grandfather clock is based on the period of oscillation of a pendulum. The clock keeps perfect time on the first floor of the Sears tower but when carefully moved to the top floor h=436 m above the surface …
6. ### Math

A clock is set right at 10 AM. The clock gains 10 minutes in 24 hours. What will be the true time when the clock indicates 3 PM the following day?
7. ### math

A clock is set right at 10 AM. The clock gains 10 minutes in 24 hours. what will be the true time when the clock indicates 3 PM the following day ?
8. ### MATHS

A clock is set right at 10PM. the clock gains 10 minutes i 24 hours. What will be the true time when the clock indicates 3PM the following day.
9. ### Maths

A clock is set right at 10AM.The clock gains 10 minutes in 24 hours. What will be the true time when the clock indicates 3PM the following day ?
10. ### Algebra 2

Neela's clock is broken the minute hand rotates around the clock correctly but the hour hand is stuck in the three o'clock position. Suppose neela first looks at the clock when the hands are aligned and it shows 3:15. She looks at …

More Similar Questions