15 points triangle tri, with a vertex r at (-4, 1), is rotated counterclockwise 90° about the origin. which of the following rotations is equivalent to 90° counterclockwise rotation about the origin? clockwise 90° counterclockwise 90° counterclockwise 360° clockwise 270°

Clockwise 270 degrees is the answer

In this exercise is given that a triangle has a vertex R at the coordinate (-4,1) and it is says that this point was rotated 90 degrees counterclockwise from the origin. It is asked to find the rotation which is equivalent to 90 degree counterclockwise rotation. 

First of all a 90 degree counterclockwise rotation is define by the rule
(x,y)--(-y,x), which means that every time a 90 degree counterclockwise rotation occurs the given point has to be changed according to the previous mention rule.

In the other hand, a 90 degree clockwise rotation is define by the rule (x,y)--(y,-x). A 360 degree counterclockwise rotation is define by (x,y)--(x,y), and a 270 degree clockwise rotation is represented by the rule (x,y)--(-y,x).

By the previous said, the rotation which is equivalent to a 90 degree counterclockwise rotation is a 270 degree clockwise rotation.

Answer: 10pi

x = central angle apc = measure of minor arc ac

the two angles x and 30 add to 180, so x+30 = 180 and x = 180-30 = 150. the measure of minor arc ac is 150 degrees.

what we need to do from here is find the circumference and then multiply it by x/360 since there are 360 degrees in a circle. in this case, x = 150, so x/360 = 150/360 = 15/36 = 5/12. the shortest distance along the curve from a to c is 5/12 of the distance around the entire circle (aka circumference)

c = circumference

c = pi*d

c = pi*24

c = 24pi

now multiply this by 5/12 to get

distance along minor arc ac = (5/12)*(circumference)

distance along minor arc ac = (5/12)*(24pi)

distance along minor arc ac = 10pi

the formula you can use is

l = (x/360)*pi*d

with

l = length of minor arc

x = central angle

d = diameter

which essentially is the steps we took though a bit differently.