Option A
is one way to determine the factors of 
by grouping
<em><u>Solution:</u></em>
Factoring by grouping means that you will group terms with common factors before factoring
<em><u>Given expression is:</u></em>
Group the first two terms together and then the last two terms together.
We can see that 
is common in first two terms
And 3 is common in last two terms
Factor them out
Thus option A is correct
For angle A, you need to do 180-130 which is 50
for angle B, you need to do 180- 90 - 50 which is 40
for angle C, you need to do 180 - 60 - 40 which is 80
If you want me to explain you with further details with how exactly I got those answers and how I knew what to do, then ask me.
an exact angle measure without approximating to a decimal value is given below.
Step-by-step explanation:
Since an angle of 2 has degree measure 360° it follows that an angle of 1 radian has degree measure (180/ )°. Likewise, an angle of size 1° has radian measure /180. We now can easily obtain a formula to convert from degrees to radians and vice-versa. To convert from degrees to radians, multiply the angle by /180.
convert decimal degrees to DMS :
- For the degrees use the whole number part of the decimal.
- For the minutes multiply the remaining decimal by 60. Use the whole number part of the answer as minutes.
- For the seconds multiply the new remaining decimal by 60.
