幅 and 高さ: width and height
Distinguish width from height without treating agreement in one dimension as identical overall size.
Stating width
幅, read はば, means width. この棚の幅は八十センチです。 says that this shelf is eighty centimeters wide.
幅を十センチ広げました。 means increasing the width by ten centimeters. It does not give a final width of ten centimeters.
Stating height
高さ, read たかさ, means height. 机の高さを調整しました。 means adjusting the height of a desk.
高さが同じ箱を選びました。 means selecting boxes of the same height. It does not establish equal widths or depths.
Comparing by dimension
幅は同じですが、高さが違います。 says that the widths match but the heights differ. Do not summarize this as identical overall size.
棚の高さを五センチ低くしました。 says that the shelf's height was reduced by five centimeters. Distinguish the change from the final height.
Does 幅を十センチ広げました give a final width of ten centimeters?
Show the answer and why
No. Ten centimeters is the increase relative to the original width.