First you need to know the definition of a complementary angle. That means that two angles add up to 90 degrees, or a right angle.
To find an angle complementary to a 78 degree angle, you need to subtract 78 from 90.
90 - 78 = 12
Answer:
A. 25 B. 45 C. 30
Step-by-step explanation:
A.
75 ÷ 3 = 25
25 × 1 = 25
B.
75 ÷ 5 = 15
15 × 3 = 45
C.
50 ÷ 5 = 10
10 × 3 = 30
Answer:
2.1
Step-by-step explanation:
Answer:
384 cm²
Step-by-step explanation:
Since it is a square pyramid, the total surface area of the pyramid is the area of its square base plus the area of its 4 triangular faces.
Area of a triangular face
= ½ ×12 ×10
= 60 cm²
Base area of pyramid
= 12 ×12
= 144 cm²
∴ Surface area of pyramid
= 4(60) +144
= 240 +144
= 384 cm²