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posledela
3 years ago
6

Math question ,how ?

Mathematics
2 answers:
Troyanec [42]3 years ago
8 0
Let x be height of the shadow
30/15 = 90/x
Do cross multiplication
30x =1350
x = 45

Let h= height of the screen
1/4 of 45 is 11.25
H = 11.25 + 45
H= 56.25

There's your answer. I hope I did it right.
Scorpion4ik [409]3 years ago
6 0
Height of the screen = x
height of the shadow = \frac{3}{4}x

ΔAEC ∼ ΔADB  ⇒

\frac{BD}{AB}= \frac{CE}{AC} \\  \\    \frac{15}{30}= \frac{ \frac{3}{4}x }{90+30} \\ \\  \frac{1}{2}= \frac{ \frac{3}{4}x }{120} \\ \\  \frac{3}{4}x = \frac{120*1}{2}=60 \\  \\ x=60: \frac{3}{4}=60* \frac{4}{3}=20*4=80 \ cm

Height of the screen is 80 cm.

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