Change -25.49 to degrees, minutes, and seconds a -25 29' 24'' b -25 31' 32'' c -25 29' 31'' d -25 32' 40''

A. -25° 29' 24"

Step-by-step explanation:

It is easier to talk about this by considering the magnitude of the angle, then applying the sign to the result.

The fractional part, 0.49°, can be multiplied by 60' per degree to get the number of minutes:

0.49° × 60'/1° = 29.4'

The fractional part of this, 0.4', can be multiplied by 60" per minute to get the number of seconds:

0.4' × 60"/1' = 24"

Then the angle is ...

-25.49° = -25° 29' 24"

Alternate solution

You can recognize this is 0.01° less than 25° 30', so is ...

0.01° × 60' = 0.6' = 0.6 × 60" = 36"

When 36" is subtracted from 25.5° = 25° 30', the result is 25° 29' 24". Of course, your angle is negative: -25° 29' 24".

Comment on base-60 arithmetic

In base-10 arithmetic, when you borrow 1 from the next higher place in the number, you are borrowing ten of the current place. For example, when you are doing arithmetic with hundreds, and you borrow 1 from the thousands place, you have effectively borrowed 10 hundreds.

In base-60 arithmetic, when you borrow one from the next higher place, you borrow 60 of the current unit. That is, borrowing one minute gives you 60 seconds. Thus, 30 minutes is the same as 29 minutes and 60 seconds. Subtracting 36 seconds from this value gives 29 minutes and 24 seconds.

The term "borrowing" was used when I learned arithmetic. More recently, I've seen it called "rewriting" the number. I also think of it as "making change": changing a higher unit to an equivalent number of smaller units.

A.

Step-by-step explanation:

-25° 29' 24"

∠cbe and ∠deb are same-side interior angles.

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