Question

find the area.
a = ? cm²
a△ = ½b·h

Explanation:

Step1: Substitute the values into the formula

The formula for the area of a triangle is \( A_{\triangle}=\frac{1}{2}b\cdot h \). Here, \( b = 21\space cm \) and \( h=8\space cm \). So we substitute these values: \( A=\frac{1}{2}\times21\times8 \).

Step2: Perform the multiplication

First, calculate \( 21\times8 = 168 \). Then, \( \frac{1}{2}\times168=\frac{168}{2} \).

Step3: Simplify the fraction

\( \frac{168}{2}=84 \).

Answer:

\( 84 \)