If a and b are two angles in standard position in quadrant i, find cos( a +b ) for the given function values. sin a = 8/17 and cos b = 12/13
-220/221
-140/221
140/221
220/221

if a and b are two angles in standard position in quadrant i, find cos( a -b ) for the given function values. sin a = 3/5 and cos b= 12/37
153/185
57/185
-57/185
-153/185

if a and b are two angles in standard position in quadrant i, find cos( a - b) for the given function values.
sin a = 15/17 and cos = 3/5
-84/85
-36/85
36/85
84/85

if a and b are two angles in standard position in quadrant i, find cos( a + b) for the given function values.
sin a = 15/17 and cos = 3/5
-220/221
-140/221
140/221
220/221

if a and b are two angles in standard position in quadrant i, find cos( a - b) for the given function values.
sin a = 4/5 and cos = 5/13
-33/65
33/65
-63/65
63/65

if a and b are two angles in standard position in quadrant i, find cos( a + b) for the given function values.
sin a = 3/5 and cos = 12/37
153/185
57/185
-57/185
-153/185

Part 1)

Part 2)

Part 3)

Part 4)

Part 5)

Part 6)

Step-by-step explanation:

the complete answer in the attached document

Part 1) we have

Determine cos (A+B)

we know that

step 1

Find the value of cos(A)

Remember that

substitute the given value

The angle A belong to the I quadrant, the cosine is positive

step 2

Find the value of sin(B)

Remember that

substitute the given value

The angle B belong to the I quadrant, the sine is positive

step 3

Find cos(A+B)

substitute in the formula

Part 2) we have

Determine cos (A-B)

we know that

step 1

Find the value of cos(A)

Remember that

substitute the given value

The angle A belong to the I quadrant, the cosine is positive

step 2

Find the value of sin(B)

Remember that

substitute the given value

The angle B belong to the I quadrant, the sine is positive

step 3

Find cos(A-B)

substitute in the formula

Part 3) we have

Determine cos (A-B)

we know that

step 1

Find the value of cos(A)

Remember that

substitute the given value

The angle A belong to the I quadrant, the cosine is positive

step 2

Find the value of sin(B)

Remember that

substitute the given value

The angle B belong to the I quadrant, the sine is positive

step 3

Find cos(A-B)

substitute in the formula

Part 4) we have

Determine cos (A+B)

we know that    

step 1

Find the value of cos(A)

Remember that

substitute the given value

The angle A belong to the I quadrant, the cosine is positive

step 2

Find the value of sin(B)

Remember that

substitute the given value

The angle B belong to the I quadrant, the sine is positive

step 3

Find cos(A+B)

substitute in the formula