Answer:
The rate of angle is 26.25 rad/sec.
Step-by-step explanation:
Given that,
First side of triangle a= 20 cm
Second side of triangle b= 50 cm
One side of a triangle is increasing at a rate = 5 cm/sec
Second side is increasing at a rate = 7 cm/s
Angle
If the area of the triangle remains constant,
We need to calculate rate of angle
Using formula of area of triangle

On differentiating

Put the value into the formula



Hence, The rate of angle is 26.25 rad/sec.