Question

At a certain rate of compound interest, Rs 250 deposited on July 1, 2018 has to accumulate to
Rs 275 on January 1, 2019. Assuming the interest rate does not change and there are no
subsequent deposits, find the account balance on January 1, 2021.

Answer 1

Answer:

(Sec A + Cos A) (Sec A - Cos A)

We know that,

(a - b) (a + b) = a² - b²

Here,

a = Sec A

b = Cos A

Substituting,

Sec² A - Cos ² A

We know that,

1 + Tan² A = Sec² A

1 - Sin² A = Cos² A

Substituting,

1 + Tan² A - (1 - Sin² A)

1 + Tan² A - 1 + Sin² A

Tan² A + Sin² A

Therefore,

\boxed{\purple{\textsf{(Sec A + Cos A) (Sec A - Cos A) = Tan² A + Sin² A}}}

(Sec A + Cos A) (Sec A - Cos A) = Tan² A + Sin² A

Answer 2

Answer:

At a certain rate of compound interest, Rs 250 deposited on July 1, 2018 has to accumulate to

Rs 275 on January 1, 2019. Assuming the interest rate does not change and there are no

subsequent deposits, find the account balance on January 1, 2021.