(1 / 3) mathematical problems such as similar triangles. (1) it is known that triangle ABC is similar to triangle DFE and the area ratio is 4:25, then triangle ABC and three (1 / 3) mathematical problems such as similar triangles （1） It is known that triangle ABC is similar to triangle DFE and the area ratio is 4:25, then triangle ABC and triangle DFE are on the corresponding sides BC and ef

(1 / 3) mathematical problems such as similar triangles. (1) it is known that triangle ABC is similar to triangle DFE and the area ratio is 4:25, then triangle ABC and three (1 / 3) mathematical problems such as similar triangles （1） It is known that triangle ABC is similar to triangle DFE and the area ratio is 4:25, then triangle ABC and triangle DFE are on the corresponding sides BC and ef

The ratio of BC to EF is 2:5
If the similarity ratio between cube A and cube B is 3:2, the ratio of their edge length is 3:2; The area ratio of the surface area is 3:2 square, that is, 9:4; The volume ratio is 3:2 cubic, that is, 27:8

In triangle ABC, we know a = 3. B = 4. C = radical 37, and find angle C Ah, my math is too bad

Using the cosine theorem, COSC = (a ^ 2 + B ^ 2-C ^ 2) / 2Ab = 9 + 16-37 / 24 = - 12 / 24 = - 1 / 2, so the angle c = 120

In the triangle ABC of mathematical problems, we know a, etc. 4, B, etc. 3C, etc. 2 to find the area of the triangle

Using cosine theorem cosa = (b ^ 2 + C ^ 2-A ^ 2) / 2BC = - 1 / 4 Sina = √ 15 / 4
S=1/2*b*c*sinA=3√15/4

In triangle ABC, a = 5, C = 7, C = 120 degrees. There should be a formula to calculate the area of triangle ABC

By the cosine theorem, there are
cosC=(a ²+ b ²- c ²)/ 2ab
Then cos120 ° = (5 ²+ b ²- seven ²) ÷(2 × 5b)
I.e. B ²+ 5b-24=0
‡ B = 3 or B = - 8 (negative values are rounded off)
△ area of ABC
S=(1/2)*ab*sinC
=(1/2) × five × three × sin120°
=15√3/4

It is known that the two sides of triangle ABC are a and B respectively, and their included angle is C (1) try to write the area expression of triangle ABC. (2) when ∠ C changes, find Maximum ABC area of triangle

If two triangles ABC are combined into a parallelogram, the side lengths of the parallelogram are a and B respectively. It is assumed that B is the bottom edge. The area of the parallelogram is B × Asin (180-c). Therefore, the triangular area is 0.5 × Absin (180-c). Maximum when C is 90 degrees

In triangle ABC, a = 13, B = 17, a = 40 degrees, find other sides, angles and areas of triangle ABC (as long as the formula)!

Cosa = (C ^ 2 + B ^ 2-A ^ 2) / 2BC find C
Then use the sine theorem a / Sina = B / SINB = C / sinc
Calculate B C
S triangle ABC = 1 / 2bcina