an angle is formed by two rays that have the same what?
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They have a common origin which is called the vertex.
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1.  When two lines cross, pairs of vertical angles are congruent.\n\n2. If two parallel lines are cut by a transbersal, alternate interior angles formed are congruent.\n\n3. If two parallel lines are cut by a transbersal, alternate exterior angles formed are congruent.\n\n4. If two parallel lines are cut by a transbersal, corresponding angles formed are congruent.\n\n5.  Opposite angles of a parallelogram are congruent.\n\n6. Base angles of an isosceles triangle or trapezoid are congruent.\n\n7. Perpendicular lines meet to form congruent angles.\n\n8.  If two angles are both congruent to a third angle, they are congruent to each other.\n\n9.  A pair of right angles are congruent. \n\n10.  Any two angles of an equilateral triangle are congruent.\n\nThere are more but most are variations of the above.
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same angle degree, same lenght of a side.
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the angle between the incident ray and the perpendicular to the reflecting or refracting surface at the point of incidence
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the four angles add up to 360 degrees
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DEFINITION: BUT FIRST IS THIS YOUR HOMEWORK ASSIGNMENT?? ANYWAYS DEF:THE ANGLE THAT A LIGHT RAY MAKES WITH NORMAL TO A SURFACE WHEN IT IS REFLECTED...
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oblique, obilisque shape
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It's too cumbersome to rewrite it all here, but check out http://www.euclideanspace.com/maths/algebra/vectors/angleBetween/index.htm\n\nThat's 2D, but the formula is the same for 3D.
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The previous answers are either wrong/incomplete/mischievious.\nFirstly there is nothing called parallel angles! You probably meant to ask what happens if the angles of two triangles are same. In that case there is no congruence/similarity between the two triangles.\nBut if two angles are equal betwen them, they are SIMILAR (same shape) and not congruent.\nIf in addition they have a side equal, they become congruent!
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it should have a right angle.\n\nThus, it's a right triangle
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Angles that are formed when parallel lines have a common intersecting line  (this intersecting line referred to as a transversal) Corresponding angles formed will have the same measure,alternate exterior angles formed, as well asalternate interior angles formed by the same transversal shall also be of the same measure. draw two parallel lines cross them both with a tranverse line at 45 degrees and you will be amased that all the corresponding angles will be 45 degrees. Simply mind bogling isn't it.
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By Thinkquest:  90°.  When one looks at a right prism, one can count all the right angles formed, and it will always be more than any non-right angles formed.
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Every point in the x,y plane has a unique set of Cartesian (rectangular) coordinates.\nSince no ray has a unique angle measure, (e.g. 30 and 390, -330, etc. all look like the same # of degrees) Polar Coordinates are not unique.
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It is called a ray.\nA ray is a half-infinite line with one end-point.
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simple  for smooth surfaces, the angle of incidence is equal to the angle of reflection\nso the angle of reflection is going to be the same angle mentioned in the question
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What you are describing is a result of light reflecting off a concave surface.  The best way to explain this is like this:\n\nDraw a big T on a piece of paper.\nNow draw a line from the lower right side to the vertex of the T (that's the intersect).  This represents light coming in.\nNow draw another line from the vertex to a point at the same location as the origin of the other line, but on the lower left.  That is the light leaving.  The angles of both lines converging on the crossing of the T should be the same.  Same with any beam of light.  It is reflected at the same angle as it is received.\n\nA spoon is a reflecting concave mirror.  If you could get close enough to the spoon you could see your image right side up.  But when you are further out than the focal distance the image inverts because the beams cross over each other.
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The direction (angle) of |u| and |v|?