15a =6a - 90
Move all the numbers with variables to one side
15a - (6a) = 6a -(6a) -90
9a = -90
9a/9 = -90/9
a = -9
Hope this helps
-3*-5 = 15
<span>When the signs are the same the answer is positive.</span>
Answer:
(C) 2√15
Step-by-step explanation:
Recognize that all the triangles are right triangles, so are similar to each other. In these similar triangles, the ratio of the short side to the long side is the same for all.
... CB/CA = CT/CB
... CB² = CA·CT = 10·6 = 60 . . . . . . . . . . multiply by CA·CB; substitute values
... CB = √60 = 2√15 . . . . . . . take the square root; simplify
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<em>Comment on this solution</em>
The altitude to the hypotenuse of a right triangle (CB in this case) divides the hypotenuse into lengths such that the altitude is their geometric mean. That is ...
... CB = √(AC·CT) . . . . as above
This is true for any right triangle — another fact of geometry to put in your list of geometry facts.
Answer:
4.5
Step-by-step explanation:
∠BAC ~ ∠EDF means that the triangles are similar. So the legs of the triangle share the same proportions, even if the sizes are different.
Since they share the same proportions, the same operations can be performed on each base to find the area.
The answer can be found with the knowledge that the area of a triangle is half of the height * width. You know the width of ∠BAC is 4, and the area is 8, so 16 (the area doubled) / 4 is the height. The width and height of ∠BAC are the same, and since the proportions are also the same, the width and height of ∠EDF are both 3. So the area is the width (3) times the height (3) divided by 2.
3*3 = 9
9/2 = 4.5
So the area is 4.5
