SVP aidez moi ! Exercice 1,2 et 3 (exercices sur la photo) Merci d'avance!

1) sinT = 35/50
sinT = 7/10
sTc = 44°

2) cos60=SH/SA
     0,5 = SH/5
   SH = 0,5*5 = 2,5cm

SHA rectangle en H
SA² = SH²+AH²
5² = 2,5²+AH²
AH²  = 18,75
AH = √18,75 = 4,3cm

3) V = pi*4,3²*2,5)/3 =
48,40cm^²


ex 3 :

developpement, je fais pas, tu dois savoir

2) (2x-3)(4x-7-2x+3)=
(2x-3)(2x-4)

3) (2x-3)(4x-7)-(2x-3)² = 12
4x²-14x+12 = 12
4x²-14x+12-12 = 0
4x²-14x = 0
2x(2x-7) = 0

2x-7 = 0
2x =7
x =7/2  =3,5cm

2x =0
x = 0