Ex. 2 :
1) NP² = MN² + MP² ⇒ MP² = NP² - MP² = 5² - 4² = 25 - 16 = 9 ⇒ NP = √9 = 3
2) Sinus angle MPN = MN / NP = 4 / 5 ⇒ angle MNP ≈ 53°
3) NB = NP - BP = 5 - 1,25 = 3,75
NA = NM - AM = 4 - 1 = 3
NB² = NA² + AB² ⇒ AB² = NB² - NA² = 3,75² - 3² = 5,0625 ⇒ NA = √5,0625 = 2,25
Bonus :
Si x = 4/3,
3x² + 5x - 3 = 3 × (4/3)² + 5 × (4/3) - 3
= 3 × 16/9 + 20/3 - (3*9)/9
= 48/9 + 60/9 - 27/9
= 81 / 9
= 9
et,
6x + 1 = 6(4/3) + 1
= 24/3 + 3/3
= 27/3
= 9