Q.Evaluate: $2\sin^230° + 3\cos^260° - \tan^245°$.

Each term is a standard value squared (or, for tangent, the value itself squared), scaled by its coefficient, then combined by ordinary arithmetic.

$2\left(\frac12\right)^2+3\left(\frac12\right)^2-(1)^2 = \frac12+\frac34-1=\frac14$.

Step 1 — read the standard values. $\sin30°=\frac12,\ \cos60°=\frac12,\ \tan45°=1$.

Step 2 — square where needed and apply the coefficients.

Step 3 — combine.

A common slip is squaring the coefficient along with the ratio (writing $2\sin^230°$ as $(2\sin30°)^2$) — the coefficient multiplies the squared ratio, it is not itself inside the square.