Найти sin a/2, cos a/2,tga/2 если знаем что cosa=3/4 a€(0;П/2)
Answers & Comments
LovelyTyan
L sin a l = sqrt(1 - cos^2a) l sin a l = sqrt(16/16 - 9/16) = sqrt(7)/4 sin a/2 = 1/2 * sqrt(7)/4 = sqrt(7)/8 cos a/2 = 1/2 * 3/4 = 3/8 tg a = sin a/cos a, tg a = [sqrt(7)/4] / 3/4 = sqrt(7)/4 * 4/3 = sqrt(7)/3 tg a/2 = sqrt(7)/3 * 1/2 = sqrt(7)/6
Answers & Comments
l sin a l = sqrt(16/16 - 9/16) = sqrt(7)/4
sin a/2 = 1/2 * sqrt(7)/4 = sqrt(7)/8
cos a/2 = 1/2 * 3/4 = 3/8
tg a = sin a/cos a, tg a = [sqrt(7)/4] / 3/4 = sqrt(7)/4 * 4/3 = sqrt(7)/3
tg a/2 = sqrt(7)/3 * 1/2 = sqrt(7)/6