â¢ equilateral - all 3 sides are equal. 2) By the types of angles they have: â¢ acute triangle - all 3 angles are acute (less than 90Â°) â¢ right triangle - has one right angle (a right angle = 90Â°) â¢ obtuse triangle - has one obtuse angle (an obtuse angle is greater than 90Â° and less than 180Â°).
Over the last 30 years, the time frame for the carving of the Grand Canyon has gone full circle. Thirty years ago, most evolutionists believed the canyon was about 70 million years old. But that estimate changed as radioisotope dating was utilized to show the plateau to be much older than the canyon itself.
Using a technique that can tell how deeply buried the canyon's rocks were at specific time intervals, scientists determined that western Grand Canyon was cut to within a few hundred meters of its present depth 70 million years ago, while eastern Grand Canyon (where most visitors see the canyon) was the site of a gorge of similar proportions to the modern canyon, but cut into Mesozoic-age rocks that are now completely stripped away.