The sum of 42 and twice a number is 164. find the number

61

Step-by-step explanation:

let the number be x then twice the number is 2x, hence

42 + 2x = 164 ( subtract 42 from both sides of the equation )

2x = 122 ( divide both sides by 2 )

x = 61

Hence the number is 61

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