Question 11857: how to use 'sin','cosin' and 'tangent'in triangles.
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! draw a right-angled triangle... a horizontal line AB and a vertical line BC at the right-end of the horizontal line. The hypotenuse is AC.
Now, draw another vertical line DE where D is some point on line AB...your choice and E is the other end of the line, somewhere on AC. OK so far?
Right, the angle A is whatever angle it is. The "interesting" or at least useful property is that the ratio of the sides in triangles ABC and ADE are the same... so AB/AC is the same as AD/AE etc.
So, we can use this fact that ratios of sides for a given angle are the same. Now there are 3 possible combinations of sides (well 6 actually). These are:
opposite/adjacent
adjacent/opposite
opposite/hypotenuse
hypotenuse/opposite
adjacent/hypotenuse
hypotenuse/adjacent
and these ratios have names:
opposite/adjacent --> tangent
adjacent/opposite --> cotangent
opposite/hypotenuse --> sine
hypotenuse/opposite --> cosecant
adjacent/hypotenuse --> cosine
hypotenuse/adjacent --> secant
For basic trig, you will use SIN, COS and TAN, the 3 "basic" ratios.
jon.
|
|
|
