angle subtended by a & b at the centre is 36 & 60 degrees respectively.then angle subtended by a+b is????

Asked by araima2001 | 30th Aug, 2016, 07:42: AM

Expert Answer:

Length space of space the space chord space left parenthesis straight l right parenthesis space equals space 2 straight r space sin open parentheses straight x over 2 close parentheses

Length space of space the space chord space space straight a space equals space space 2 straight r space sin open parentheses fraction numerator 36 degree over denominator 2 end fraction close parentheses equals 2 straight r space sin open parentheses 18 degree close parentheses

Length space of space the space chord space space straight b space equals space space 2 straight r space sin open parentheses fraction numerator 60 degree over denominator 2 end fraction close parentheses equals 2 straight r space sin open parentheses 30 degree close parentheses equals 2 straight r cross times 1 half equals straight r

Suppose space chord space straight a plus straight b space substends space angle space straight theta space at space the space centre.


Length space of space the space chord space straight a plus straight b space equals space Length space of space the space chord space space straight a space plus Length space of space the space chord space space straight b
2 straight r space sin open parentheses straight theta over 2 close parentheses space equals space 2 straight r space sin open parentheses 18 degree close parentheses space plus space straight r
2 space sin open parentheses straight theta over 2 close parentheses space equals space 2 cross times left parenthesis 0.3090 right parenthesis plus 1
2 space sin open parentheses straight theta over 2 close parentheses equals 1.618
space sin open parentheses straight theta over 2 close parentheses equals 0.809
straight theta over 2 space equals space sin to the power of negative 1 end exponent open parentheses 0.809 close parentheses
straight theta over 2 space equals space 53.99 degree almost equal to 54 degree
straight theta equals 108 degree


Option space left parenthesis straight b right parenthesis space is space correct.
 
 
 
 

Answered by Vijaykumar Wani | 30th Aug, 2016, 12:24: PM

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