Find the value of x.
1 answer:
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Answer:
40°
Step-by-step explanation:
The reference angle is the positive acute angle created by the terminal arm and the x-axis.
The highlighted red in the picture below shows what we're looking for.
The arm rotated 220° (but 'backwards' so the value given is negative).
|-220°| - 2(90°) <= Subtract two right angles for two quadrants
= 220° - 2(90°)
= 220° - 180°
= 40°
Therefore, the reference angle is 40°.
If you got 50°, you probably calculated the angle with the terminal arm and the y-axis. Remember to always use the nearest side of the x-axis!
Step-by-step explanation:
Let the two-digit number is
<u>This can be written as:</u>
- 10x + y, where 1 ≤ x ≤ 9 and 0 ≤ y ≤ 9
<u>The difference between the number and product of its digits is:</u>
- d = 10x + y - xy
<u>Rewrite this as below:</u>
d = 10x - xy + y - 10 + 10 =
x(10 - y) - (10 - y) + 10 =
(x - 1)(10 - y) + 10
<u>We see that:</u>
- 0 ≤ x - 1 ≤ 8 according to the condition given above
- 1 ≤ 10 - y ≤ 10 again according to the condition given above
<u>The value of d is then:</u>
- 0 + 10 ≤ d ≤ 8*10 + 10
- 10 ≤ d ≤ 90