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MATHS~8
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http://pic.fksite.com/1181310036.JPGhttp://pic.fksite.com/1181310099.JPG〔the radius of a circle is 8 cm . a new circle is formed by increasing the radius by 10%(ａ)find the area of the new circle in terms as ΤΤ.〕1.given that tan 48度=1/tan2Θ,findΘ.2.find the value of cos^28度+cos^62度without... 顯示更多 http://pic.fksite.com/1181310036.JPG http://pic.fksite.com/1181310099.JPG 〔the radius of a circle is 8 cm . a new circle is formed by increasing the radius by 10% (ａ)find the area of the new circle in terms as ΤΤ.〕 1.given that tan 48度=1/tan2Θ,findΘ. 2.find the value of cos^28度+cos^62度without using a calculator.
最佳解答:
a)The radius of the new circle =8x1.1 =8.8cm The area of the new circle =ΤΤxr^ =ΤΤx8.8^ =ΤΤx77.44 =243.3cm^(cor.to 1 d.p.) 1.tan 48度=1/tan2Θ tan2Θ=1/1.1106 2Θ=42度 Θ=21度 2.cos^28度+cos^62度 =cos^(28度+2度)+cos^(62度-2度) =(開方3/2)^+(1/開方2)^ =3/4+1/2 =1.25
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其他解答:
(a) The area of the new circle is : TT x R^2 = TT x [ 8 x (1+10%) ]^2 = TT x [8 x 1.1]^2 = TT x 8.8^2 = 77.44 TT 問題1和2, 暫時唔識答! :D
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