百科全書

標題:

MATHS~8

發問:

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

• 一d 2008北京奧運既資料~★☆有20點
• 特務S嘜how much--
• w850i一問

• 一d 2008北京奧運既資料~★☆有20點
• 特務S嘜how much--
• w850i一問

 

此文章來自奇摩知識+如有不便請留言告知

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