## rinoa1989 2 years ago Hi I need help for a question here related to Circle as attached below. Please help Thanks! ><"

1. rinoa1989

2. hartnn

do you know the central angle and corresponding arc property ...like |dw:1359727764547:dw| if central angle given is 70 degrees ,say, then can you find length of arc p and angle q ?

3. hartnn

i meant length of arc q and angle p...

4. amistre64

you can create isocolese triangles from central angles.|dw:1359728013730:dw|

5. hartnn

for your question, i extended WO to meet circle at say L |dw:1359727980102:dw|

6. amistre64

i think working the iso triangle with the 65 would be simpler :)

7. amistre64

|dw:1359728146814:dw|

8. hartnn

oh, but i figured it out the using other method, i think..and i donno how that would help...maybe you can proceed to show us...

9. rinoa1989

omg looks so complicated! LOL ><"

10. amistre64

the base angles of an iso tri are equal; leaving the central angle to be 180 - 2base; in this case, 180 - 2(65) total arc length is then 70 + 180 - 2base and x is determined to be half that

11. hartnn

yeah...i figured arc WV = 50 using similar thing, which is essentially similar to what u did..

12. hartnn

my way... arc WV+VU+UL = 180 but since angle LWV = 65 , VU+UL = 130 which gives WV = 50 then 2x = 70 +WV

13. hartnn

14. rinoa1989

wait let me digest first lol

15. rinoa1989

i duno how u get this arc WV+VU+UL = 180

16. hartnn

since is O the centre, arc WL is semicircle WL = 180 WV+VU+UL = 180

17. rinoa1989

ic ok how bout this one 2x = 70 +WV ??

18. hartnn

|dw:1359729747346:dw| so 2x = 70+WV

19. hartnn

thats why i first asked you whether you know that property....

20. hartnn

still don't get it ?

21. rinoa1989

sorry i duno about that property i tot it is related to the photo i attach here

22. hartnn

its the same property i illustrated.. angle A = x= 1/2 of central angle O(2x) = 1/2 of arc QP so, here x = half of arc TV x= TV/2 2x=TV = 70+WV....

23. rinoa1989

oops ic ok! coz i just use the 70 to divide 2 to find x now i understand thank you so much for your time in explaining! ><"