Mathematics
Answer
Let first term of A.P. be a and common difference be d.
By formula,
an = a + (n - 1)d
Given,
Ninth term of an A.P. is zero.
⇒ a9 = a + (9 - 1)d
⇒ 0 = a + 8d
⇒ a = -8d ………(1)
29th term = a29
= a + (29 - 1)d
= a + 28d
= -8d + 28d
= 20d.
19th term = a19
= a + (19 - 1)d
= a + 18d
= -8d + 18d
= 10d.
Since, 29th term = 20d = 2 × 10d = 2 × a19.
Hence, proved that 29th term is twice the 19th term.
Related Questions
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(i) co-ordinates of vertices B and C.
(ii) equation of line through vertex C and parallel to side AB.
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sin A(1 + tan A) + cos A(1 + cot A) = sec A + cosec A
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