Which ones are correct or incorrect? thanks! :)

Answers:

Explanation:

A)

The first letter of any ray must be the endpoint. So we must start with point Q and nothing else. The ray names for this could be "ray QR "or "ray QS". So there's no way we can start with point S as it's not an endpoint. The order matters when it comes to naming rays.

B)

When naming a segment, we just list the two endpoints. The order doesn't matter (in contrast to a ray where it does matter). So "segment SQ" is one valid name for this. The other valid name is "segment QS".

C)

Assuming all three points on the same plane, then we can name this plane SRQ. The order of the letters doesn't matter. You need 3 points to define a plane. The points must all be in the plane and the points cannot be on the same line (aka they can't be collinear).

D)

We cannot name a line with simply one point. There isn't enough info to determine where the line is aimed with just one point. Imagine the line able to spin around point Q (like a propeller blade). As you can see, we cannot nail down the line. However, having two different points will be able to nail down the line.

In short: you need 2 points to define a line.

The same goes for a line segment and a ray.

the equation cos(35) =a/25 can be used to find the length of bc what is the length of bc? round to the nearest tenth

step-by-step explanation:

hello!

to begin with, we're given that on earth, a rock weighs 20 pounds, and while on jupiter, that same rock weighs 42 pounds. now, we're trying to find the weight of a rock that weighs 10.5 pounds on earth, on jupiter.

to solve this, first, set up a proportion, cross-multiply, and solve it algebraically.

setting up the proportion is the hardest and the most confusing part of the problem, but it's simple.

if on earth, the rock weighs 20 lbs, and on jupiter it weighs 42 lbs, our first part of our proportion is 20/42 lbs. the second part has to be equal to each other. this means that 10.5 has to be on the numerator of the fraction, and x, the value we're trying to find, has to be on the denominator. remember that the rock weighs 10.5 lbs on earth, and we're trying to find the weight of it on jupiter (which is x).

20/42 = 10.5/x

next, you would cross-multiply.

20x = 42(10.5)

20x = 441

now, solve it algebraically by using division.

x = 22.05 lbs

this can be rounded to 22.1 lbs.

therefore, the weight of the rock on jupiter is 22.1 lbs, the fourth choice.