Question

Find the sum of the first 20 terms of the Arithmetic sequence as a= 7; tl=3; and n=20.

Answer 1

Answer:

Step-by-step explanation:

let angle be x°

then it's complement is 5÷4x

5÷4x+x=90°

5x×1+x×4÷4=90°

9x÷4=90°

x=40°

5÷4x

5÷4×40°

50°

Check=

50°+40°=90°

hope this helps

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Answer 2

Given,

$\rm{}a = 7 \\ \rm{}a_l = 3 \\ \rm{}n = 20$

Therefore,

Required Sum of the terms in the AP is :

$\bf{S_n = \frac{n}{2} \bigg(a + a_{\tiny{l}}\bigg) } \\ \\ = > \frac{20}{2} \bigg(7 + 3 \bigg) \\ \\ = > 10 \times (10) \\ = > \sf \green{ 100}$