Cos²α+cos²β+cos²γ=1
cos²γ=1-cos²α-cos²β=1-cos²120°-cos²45°=1-(1/2)²-(√2/2)²=1-1/4-1/2=1/4
cosγ₁=1/2 cosγ₂=-1/2 поскольку α=120°, т.е. координата по х<0, то
γ=-60°=300°.
1.log(5)1/25+2lg0,1=log(5)1/5^2+2lg1/10=log(5)5^-2+2log(10)10^-1=-2-2=4
2. log(3)log(2)8=log(3)log(2)2^3=log(3)3=1
[tex] - log_{10}(x) = - log_{10}(18) - log_{10}(4.9) \\ - log_{10}(x) = - ( log_{10}(18) log_{10}(4.9) ) \\ - log_{10}(x) = - log_{10}(88.2) \\ x = 441/5
8х-(2х+5)+(х-1)=<span>8х-2х-5+х-1=7х-6</span>
Integral (-1...1) (1-x^2)dx=x-1/3x^3(-1...1)=4/3