Is there a way to calculate sin, cos, and tan without a calculator?

if so, could you do it with this

tan(90°) = de/4

also, could you explain it step by step.

!

  yes, and no

Step-by-step explanation:

There are a few trig functions that are "simple" and can be memorized. Usually, these are the ones for angles of 0°, 30°, 45°, 60°, 90°. See below for a table.

To solve an equation like this for DE, you multiply both sides of the equation by 4 (cancelling the denominator).

  4·tan(90°) = DE

The tangent of 90° is "infinity." So, the length of DE will be infinite for an angle of 90°.

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Trig functions of multiple angles and half angles can be derived from those in the table using the appropriate formulas. The math can get messy fast.

Of course, SOH CAH TOA reminds you of the relationships between trig function values and right triangle side measures. You may not know the angle measure (and it may be irrelevant), but you can find the trig function value.

V=lwh=5 x 9 x 3=135cm3