Cuboids:
Let length = l, breadth = b and height = h units. Then,
Volume = (l × b × h) cubic units.
Surface area = 2 (lb + bh + lh) sq. units.
Diagonal = √(l2+b2+h2) units.
Cube:
Let each edge of a cube be of length a. Then
Volume = a3 cubic units.
A clock has two hands; the smaller one is called the hour hand or short hand while the larger one is called the minute hand or long hand.
In 60 minutes, the minute hand gains 55 minutes on the hour hand.
In every hour, both the hands coincide once. In 12 hours they coincide 11 times.
The hands are in the same straight line when they are coincident or opposite to each other.
When the two hands are at right angles, they are 15 minutes space apart.
When the hands are in opposite directions, they are 30 minutes spaces apart.
Angle traced by hour hand in 12 hrs = 360º.
Suppose a man has to pay Rs. 156 after 4 year and the rate of interest is 14% per annum. Clearly, Rs. 100 at 14% will amount to Rs. 156 in 4 years. So, the payment of Rs. 100 now will clear off the debt. of Rs. 156 due 4 years hence. We say that Sum due = Rs. 156 due 4 years hence.
Present worth (P.W) = Rs. 100
True Discount (T.D) = Rs. (156 – 100)
= Rs. 56 = (Sum due) – (P.W).
We define: T.D = Interest on P.W.
Amount = (P.W) + (T.D).
Interest is reckoned on P.W. and true discount is reckoned on the amount.
Important Formula:
Let rate = R % per annum and Time = T years. Then
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