Question

在锐角三角形ABC中，abc分别为角ABC所对的边，且根号3倍A等于2倍的c乘sinA，若c等于根号7，三角形ABC的面

在锐角三角形ABC中，abc分别为角ABC所对的边，且根号3倍A等于2倍的c乘sinA，若c等于根号7，三角形ABC的面积为2分之3倍根号3，求a+b的值

Answer 1

在锐角三角形ABC中，abc分别为角ABC所对的边，且根号3倍A等于2倍的c乘sinA，若c等于根号7，三角形ABC的面积为2分之3倍根号3，求a+b的值
解析：∵√3a=2csinA，c=√7
∴csinA=√3/2a
∵S(⊿ABC)=3√3/2=1/2bcsinA=1/2ab√3/2==>ab=6
由正弦定理a/sinA=c/sinC==>sinC=a/(csinA)=√3/2==>C=60°
由余弦定理c^2=a^2+b^2-2abcosC
∴a^2+b^2-ab=7=(a+b)^2-3ab=(a+b)^2-18
∴a+b=5

Answer 2

由√3a=2csinA，当c=√7时：
√3a=2√7sinA，
∴sinA=√3a/2√7=√21a/14.
△ABC面积S=（1/2）bcsinA
=（1/2）b×√7×√21a/14
=ba√3/4=3√3/2
∴ab=6.
a取2，b取3，△ABC是锐角三角形。
a+b=5.

Answer 3

(1)
由√3a=2csinA，当c=√7时：

√3a=2√7sinA，

∴sinA=√3a/2√7=√21a/14.

△ABC面积S=（1/2）bcsinA

=（1/2）b×√7×√21a/14

=ba√3/4=3√3/2

∴ab=6.

a取2，b取3，△ABC是锐角三角形。

a+b=5.

(2)
在锐角三角形ABC中，abc分别为角ABC所对的边，且根号3倍A等于2倍的c乘
sinA，若c等于根号7，三角形ABC的面积为2分之3倍根号3，求a+b的值

解析：∵√3a=2csinA，c=√7

∴csinA=√3/2a

∵S(⊿ABC)=3√3/2=1/2bcsinA=1/2ab√3/2==>ab=6

由正弦定理a/sinA=c/sinC==>sinC=a/(csinA)=√3/2==>C=60°

由余弦定理c^2=a^2+b^2-2abcosC

∴a^2+b^2-ab=7=(a+b)^2-3ab=(a+b)^2-18

∴a+b=5

Answer 4

It is ture, I am being normal and normal. Like that day I may had great ambition,moncler giubbotti, I thought I will be a big big person who everyone may know, I thought I can earn a lot of money every day and I won't worry about the life, I imaged different kinds of the future, all of them are very beautiful.
But when the day comes,sale ugg, when today that the day I've gradute for 3.5 years,moncler jassen online, I find out the reality is really not easy. I do not have a rich father or may can be say I just have a father who is really not love at me who always very selfish to pursuit his own beautiful life and forget his original family. Anything I should depend on myself. I try to find good job which can give me a lot of income but what the job I have is the very very ordinary,moncler prezzi, I almost can not make enough money for the paying every month. I feel very very disappointed and failure.
But I always encourage myself shall be adamant. To be hard, to believe tomorrow will be very beautiful.