Question

ctgB(1-cos2B) решите пожалуйста подробно

Answer 1

ctgB (1-cos2B)=ctgB (1 - cos^2B +sin^2B) = ctg* 2sin^2B =( cosB* 2sin^2B)/ sinB = 2sinBcosB =sin2B

Answer 2

Можжно и через Cos

Answer 3

ctB(1-cos2B)= cosB/sinB*( sin^2B + cos^2B-сos^2B+sin^2B)= cosB/sinB*(2sin^2B)= cosB*2sin^2B/sinB= 2cosBsinB= sin2B