Trigonometry is basically formula's to help you find out unknown sides and angles of a triangle. Surveying is measuring land. But as not all land is equal so these formula's are used to help.
Trigonometry is used depending on what the problem is.
Measure an angle!
An acre is the unit used to measure land usually.
Trigonometry is used effectively in electronics.
Measuring land area.
You could measure the sides of a shape and use trigonometry.