Question

Daca intr-un trapez baza mica are lungimea egala cu media geometrica a numerelor4 cm si 9 cmsi baza mare are lungimea egala cumedia aritmetica a numerelor 12 cm si 28 de cm, atunci lungimea liniei mijlocii va fi egala cu ....cm?

Answer 1

b=√4*9=6 cm
B=√12*28=√336 cm=4√21
linia mijlocie=(6+4√21)/2=3+2√21

Answer 2

Fie trapezul ABCD, AB||CD, AB>CD

$AB=\dfrac{12+28}{2}=20\ m$

$CD=\sqrt{4\cdot9} =2\cdot3=6\ cm$

Fie MQ - linia mijlocie


$MQ=\dfrac{AB+CD}{2} = \dfrac{20+6}{2}= \dfrac{26}{2} = 13\ cm.$