- In geometry and trigonometry, a right angle is an angle of exactly 90 degrees or đ/2 radians corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles. The term is a calque of Latin angulus rectus; here rectus means “upright”, referring to the vertical perpendicular to a horizontal base line.
- Stephen Mather Wilderness (Wikipedia)
The Stephen Mather Wilderness is a 634,614 acres (256,819 ha) wilderness area honoring Stephen Mather, the first director of the National Park Service. It is located within North Cascades National Park, Lake Chelan National Recreation Area, and Ross Lake National Recreation Area in the North Cascade Range of Washington, United States.
