H E L P P P P P P P PP P P P P P P P P P P P PP. PP. P PP P P P P P P P P P P P P P P P P PP P. PP P P P P P P P. P P

x≈7.5

Step-by-step explanation:

Part A:

Let's call the missing side of x:

5²+x²=9²

25+x²=81

x²=56

x= square root of 56

x≈7.5

Part B:

The sum of the internal angles of a triangle is always 180°, and the square in the top angle means that it is 90°, so:

90°+21°+y=180°

y=180°-90°-21°

y=69°

any options?

step-by-step explanation:

answer: cos [   arcsin (3/5) - arccos (1/2) ] =

step-by-step explanation: × = 3/5 = 0.6--> x = 36.87 and x = 180 - 36.87 = 143.13 deg

cos y = 1/2 --> y = +- 60 deg a. cos (x - y) = cos (143.13 - 60) = cos 83,13  

=

0.12

b. cos (36.87 - 60) = cos (-23.23) = 0.92