ABCD is a quadrilateral with AD = BC, AB = 40, CD = 20 and ∠A + ∠B = 90. Find the area of the quadrilateral.
(In reply to
Solution by Jer)
Calling E the intersection point of lines AD and BC. Looking the figure on the basis of the data you see that ECD angles are 90 45 45. As CD =20 then EC=ED=10sqr2
Then
AE=AD+ED=40cos(a) [a angle A]
BE=BC-EC=40sen(a)
Easely AD=10sqr6 a=15°
The Area ABCD is then 300
Edited on December 20, 2018, 6:16 pm
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Posted by armando
on 2018-12-20 18:15:39 |
re: Solution
