Look at the pictures. Listen and repeat. Which of them sound similar in your language? Do you have them in your country?

Из треугольника САН sinA = CH/AC => CH = √7/4 * 4 = √7
по теореме Пифогора:
АН² = СА² - СН²
АН² = 16 - 7 = 9 => AH = √9 = 3
ответ 3