The Exact Value of tan 22.5 degrees (4 of 5)

The exact value of tan 22.5deg = -1+√2, can be solve by using the tangent function's double-angle formula tan [2(theta)] = [2(tan theta)]/[1-(tan theta)^2], where theta = 22.5 deg, in which we can find a quadratic equation. By employing the Quadratic Formula, we can then find the exact value of tan 22.5deg = -1+√2.

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