Answer:
a = 10
Explanation:
CF is a straight line , so the 3 angles on it sum to 180° , then
∠ BOA = 180° - (90 + 40)° = 180° - 130° = 50°
∠ DOE = ∠ BOA ( vertical angles ) , then
5a = 50 ( divide both sides by 5 )
soln
let one side be c
let another side be d
then
40=d(vertically opposite angle)
5a =c(vertically opposite angle)
again
c+90=180(being linear pair)
or, c=180-90
therefore, c=90
finally
let c be a
5a=5×90
=450
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