D. The Pythagorean Theorem
If the triangle is a right triangle, where one angle is equal to 90o, Then you can use the Pythagorean Theorem. To use this, label each side of the right triangle a, b, and c, in which c is the hypotenuse/longest side/side opposite of the 90o angle; a2+b2=c2 . Just input the values into this equation and you are able to get one side as long as you know the other two. If the triangle is not a right triangle, then you would need to know an angle of one of the sides already known in order to use the law of cosines.
Yes
Acute triangle - all of the angles are less than a right angle (90°).Scalene triangle - none of the sides or angles are congruent. It can be shown that if no two angles are the same, then no two sides are the same using the Law of Sines and Law of Cosines.
a right triangle has one right angleA triangle with a right angle is a right triangle.
A triangle with 1 right angle is a right angle triangle.
cosine = adjacent/hypotenuse
Trigonometric ratios, by themselves, can only be used for right angled triangles. The law of cosines or the sine law can be used for any triangle.
If it's a right triangle, use pythagorean's theorem (a2+b2=c2) to solve it. = If it's an oblique triangle, use the law of sines or cosines (see related link)
Law of sines or cosines SinA/a=SinB/b=SinC/c
Yes. Look up the law of sines and the law of cosines as examples. there are also formulas that can find out the area of a non-right triangle.
When none of the angles are known, and using Pythagoras, the triangle is known not to be right angled.
Having sufficient angles or sides one can use either, The Law of Sines, or, The Law of Cosines. Google them.
Yes
a2+b2=c2, but that only works for right triangles, where c is opposite the right angle. The law of cosines, see Related Link below, will help for non right triangles, but you need to know one of the angles.
The law of cosines with a right angle is just the pythagorean theorem. The cosine of 90 degrees is 0. That is why the hypotenuse squared is equal to the sum of both of the legs squared
If the triangle is a right triangle, where one angle is equal to 90o, Then you can use the Pythagorean Theorem. To use this, label each side of the right triangle a, b, and c, in which c is the hypotenuse/longest side/side opposite of the 90o angle; a2+b2=c2 . Just input the values into this equation and you are able to get one side as long as you know the other two. If the triangle is not a right triangle, then you would need to know an angle of one of the sides already known in order to use the law of cosines.
Yes