Answer. A quadrilateral is any polygon with four sides. A rectangle, by definition, is a polygon with four sides and four right angles. Every rectangle is a quadrilateral because all rectangles must have four sides, which is the definition of a quadrilateral. what is photosynthesis
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b

explanation:

mitosis

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

a:

by the combination of an unlimited number of elements

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.