2cos²a - 1 = 2cos²a - sin²a - cos²a = cos²a - sin²a = cos2a
<span>( 1.8 * 10 -³ ) * ( 3 * 10 в 5 степени )=1,8*3*</span>tex] 10^{-3} [/tex]*
=5,4*
=540
tgα=sinα/cosα
sin²α+cos²α=1
sin²α+(√10/10)²=1
sin²α=1-1/10
sin²α=9/10
sinα=+-√(9/10)
α∈(3π/2;2π), =>sinα<0
sinα=-√(9/10), sinα=-3/√10
tgα=(-3/√10)/(√10/10)
tgα=-3
5^4*125^10=5^4*(5^3)^10=5^4*5^30=5^34