Answer:
21 inches
Step-by-step explanation:
refer to attached graphics
we can find the height by the Pythagorean theorem.
diagonal² = width² + height²
height² = diagonal² - width²
we are given that diagonal = 29" and width = 20", hence
height² = 29² - 20²
height² = 841 - 400
height² = 441
height = √441 = 21 inches
