Geometry
noun
How many? What? In this area of study, you ask these questions a lot. This area of study is geometry, because you have to ask how many sides and how much the area is or something (can you tell I don't remember any maths?).
The 学 is read correctly, in terms of what you learned. The 幾 and 何 is weird, though. Just think how when you're asking a question in Japanese, you end the sentence with か. So, it's like, "何か????" and that's why it becomes か. Then, for 幾 think about how the key (き) to answering geometry questions correctly is figuring out "how many" sides something has. So, "do you have the keyか?"
幾何学のテストでAプラス取ったの？すごいじゃん、よくやったね！
Did you get an A+ on the geometry test? That's amazing, you did really well!
幾何学模様のカーペットが欲しいんだよね。
I want a carpet with a geometric pattern.
幾何学的な図形を描くために、コンパスと定規を使いました。
I used a compass and ruler to draw a geometric shape.
幾何学とは、図形の性質や空間の構造を研究する数学の一分野です。
Geometry is a branch of mathematics that studies the properties of shapes and the structure of space.