Pauline,

A basic foundation in trigonometry is pretty necessary for Calculus. Many of my peers struggled with certain problems that required them to use trigonometry, a class they had not taken yet. I would suggest, based on my own experience, that you take trigonometry.

Yes, definitely do all the trigonometry you can before entering calculus. Trigonometric functions show up everywhere in Calculus. Also, focus on angle measurement in radians, not degrees. All of the use of trigonometry in Calculus is in radians, and eventually, when you get to Power Series right at the end of Integral Calculus (called Calculus 2 in some non-Khan Academy sources), you will learn the beauty of the connection between trigonometry and some of the elements of numbers as a result of using radians.

Also be sure to master the inverse trigonometric functions, such as arccos, arcsin, and arctan, because these come up in some differentiating and integration topics in Calculus.

From Geometry, you may want to learn or refresh your knowlege of volumes of solids.

Good luck in your studies!