so easy question, but i wanna kno the shortest solving way.
2006-09-12 19:40:14 · 4 answers · asked by free aung san su kyi forthwith 2 in Science & Mathematics ➔ Mathematics
we can write cos200=cos(180+20)
=> - cos20=p ('coz 200 degree angle lies in IIIrd quadrant & there cos is -ve)
therefore cos20 = - p
or sin(90-20)= - p ('coz cosx = sin 90-x)
=> sin70 = -p
on squaring both sides, we get
(sin70)^2 = (-p)^2 = p^2
also we can write
cos70=sqrt(1-sin70^2)=sqrt(1-p^2)
thus cot70=cos70/sin70
= sqrt(1-p^2)/(-p)
2006-09-12 21:10:52 · answer #1 · answered by reu_999 2 · 0⤊ 0⤋
cos200=cos(180+20)=-cos20=p given
then cos20=-p
or, cos (90-70)=-p
or, sin70=-p
cos70=(1-sin70^2)^1/2=(1-p^2)^1/2
then cot70=cos70/sin70= - p / (1-p^2)^1/2
2006-09-13 03:05:27 · answer #2 · answered by saby 2 · 0⤊ 0⤋
cos200=-cos20=-p
sin20= - sqrt(1-p^2)
cot 70=cos70/sin70=sin20/cos20=sqrt(1-p^2)/p
Hint: sin x=cos(90-x)
2006-09-13 02:55:45 · answer #3 · answered by iyiogrenci 6 · 0⤊ 0⤋
cos200=p
cos200=1/cot200
1/cot200=p
2006-09-13 06:02:09 · answer #4 · answered by Jonathan N 3 · 0⤊ 0⤋