Where do the sun’s rays hit earth’s surface nearly at right angles?

The Sun's rays hit the Earth's surface nearly at right angles at the Earth's equator.
During equinox periods in March and September, the Sun's rays hit the Equator at a perpendicular angle because the Sun is in a position in the sky directly over the Earth's equator. This in turn means that the Sun's rays hit the Earth’s surface nearly at right angles

Argon, carbon-14, and carbon-12