First of all, add a topic, O is the center of the circle (the following ideas for solving problems are based on the condition that O is the center of the circle)

Connect OP first, then make the vertical line of AO and CO through p, and cross AO to m, CO and n respectively.

At this time, you will find that the quadrilateral OCPA is divided into two triangles, AOP and COP.

S triangle AOP = ao * pm *1/2 = 5 * pm *1/2.

S triangle COP = co * pn *1/2 = 5 * pn *1/2.

S quadrilateral OCPA=5* 1/2*(PM+PN)

For the convenience of calculation, let PM=x and pn = y.

Because AB is perpendicular to CD, PM is perpendicular to AB, and PN is perpendicular to PN, the quadrilateral PMON is a rectangle, so Mo = PN = Y.

Because PO=5, x 2+y 2 = 25.

Because AO=5, MO=y, AM=(5-y)

Because AP=4, X 2+(5-y) 2 = 16 can be obtained by right triangle APM.

Combined with the above formula X 2+Y 2 = 25, y=3.4= 17/5 can be calculated.

Similarly, we can use x = 4/5 to calculate the radical number 21= (4/5) * (21(1/2)) (here, it's just a matter of expression. 12 times of 2 1 is the root number 2 1).

According to s quadrangle OCPA = 5 *1/2 * (PM+PN) = 5 *1/2 * (4/5) * (21(2))+17/.