Start off by restating: Historians know about the past before there were written records by studying artifacts The three main types of artifacts are physical, visual, and oral traditions.

Two lines that do not intersect are skew. always sometimes or never

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

Define the type of sequence below. 7, 14, 28, 56, 112, a. neither arithmetic nor geometric b. arithmetic c. both arithmetic and geometric d. geometric