Question

ma puteti ajuta va rog frumos...​

Answer 1

3. Ecuatia are 2 radacini reale distincte daca Δ > 0

Δ = b² -4ac =144 -4*9*m² = 144 - 36m²

144 -36m² > 0

-36m² > 144

-m² > 4

m² < -4

m < -2

m apartine (-2, infinit)

5. AB = V(xB - xA)² + (yB-yA)² = V(0-3)² + (5-1)² = V(9+16) = V25 = 5

BC = V(xC-xB)² + (yC-yB)² = V(0-0)² + (1-5)² = V16 = 4

AC = V(xC-xA)² + (yC-yA)² = V(0-3)²+ (1-1)² = V9 = 3

Teorema lui pitagora

AB² =BC² + AC²

25= 16 + 9

25 = 25 => triunghiul ABC este dreptunghic

6. sin²x + cos² x = 1

cos²x = 1-sin²x

cosx = ± V(1-sin²x)

cos x = ± V[1- (2V2/3)² ]

cosx = ± V[1 - 8/9]

cosx = ±V[9/9-8/9]

cos x = ±V1/9

cosx = ± 1/3

Cum x apartine (0,pi/2 )primul cadran unde cos x ia doar valori pozitive => cos x = 1/3