f4sinx
2007-01-19 3:56 pm
sin A & cos A (A is between 180degree and 270 degree) are the roots of the equation 25x^2+hx+12=0 , find the value of h.
回答 (1)
2007-01-19 4:05 pm
✔ 最佳答案
from the question, we havesin A +cos A=-h/25
(sin A )(cos A)=12/25
since
(sin A+cos A)^2
=sin^2A+cos^2A+2(sin A )(cos A)
=1+2(sin A )(cos A)
So
(h/25)^2=1+2(12/25)
(h/25)^2=49/25
h^2=49*25
h=35
收錄日期: 2021-04-25 16:51:39
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https://hk.answers.yahoo.com/question/index?qid=20070119000051KK00469