Answer:
90degrees
Step-by-step explanation:
To get the measure of angle C, we will use the cosine rule as shown;
AB² = AC²+ BC² - 2(AC)(BC)cos C
85² = 13²+ 84² - 2(13)(84)cos C
7225 = 169 + 7056 - 2184cosC
7225 - 7225 = -2184cosC
0 = -2184cosC
cosC = -0/2184
cosC = 0
C = arccos0
C = 90degrees
Hence the measure of angle C is 90degrees
