Answer:
Step-by-step explanation:
In the diagram below we have
ABCD is a parallelogram. K is the point on diagonal BD, such that
And AK meets BC at E
now in Δ AKD and Δ BKE
∠AKD =∠BKE ( vertically opposite angles are equal)
since BC ║ AD and BD is transversal
∠ADK = ∠KBE ( alternate interior angles are equal )
By angle angle (AA) similarity theorem
Δ ADK and Δ EBK are similar
so we have
( ABCD is parallelogram so AD=BC)
( BC= BE+EC)
( subtracting 1 from both side )
taking reciprocal both side
Given AP is 21 ,18,15,...
First term = 21
Common difference = 18-21 = -3
Let an = -81
We know that
an = a+(n-1)d
⇛21+(n-1)(-3) = -81
⇛ 21-3n+3 = -81
⇛24-3n = -81
⇛ 24+81 = 3n
⇛ 105= 3n
⇛ n = 105/3
⇛ n = 35
35th term of the AP is -81.
<u>also</u><u> read</u><u> similar</u><u> questions</u><u>:</u> Which term of a AP 5 , 13 , 21 ,... is 181?
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Which term of the AP:3, 8, 13, 18,...,is 78?
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The answer would be C. $27.20