bonjour,
A = √2(√2+5√3)
= √2*√2 + √2*5√3
= 2+5√6
B = √24+√9+√54
= √4√6+3+√9√6
= 2√6+3+3√6
= 3+5√6
exo 4 :
cos²(x)+sin²(x) = 1
(0,8)² +sin²x = 1
0,64+sin²(x) = 1
sin²(x) = 1-0,64
sin(x) = √0,36 = 0,6
tan(x) = sin(x)/co(x)
= 0,6/0,8 = 4/3 ( on laisse en fraction)
