Equation (3.7) Page 24
Equation (3.7) should be
$$
A(ABD)>A_\text{wedge}(ABD)>A(ABC)
$$
Equation (3.8) Page 24
Equation (3.8) should be
$$
\frac{1}{2}\tan \alpha > \frac{\alpha}{2} > \frac{1}{2}\sin \alpha
$$
Equation (3.7) should be
$$
A(ABD)>A_\text{wedge}(ABD)>A(ABC)
$$
Equation (3.8) should be
$$
\frac{1}{2}\tan \alpha > \frac{\alpha}{2} > \frac{1}{2}\sin \alpha
$$