Answer:
Step-by-step explanation:
These are geometric means problems. In the top one, a is the geometric mean as the height for both the smaller triangles inside the big one. Therefore,
[tex]\frac{4}{a} =\frac{a}{25\\}\\a^2=100\\a=10[/tex]
The next one has the geometric mean of b, being a part of the smaller triangle on the left and the big triangle as a whole:
[tex]\frac{4}{b} =\frac{b}{29}\\b^2=116\\b=10.77[/tex]
